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Chronic neutropenia causes involve nutritional deficiencies and inborn errors of immunity(IEI), such as severe congenital neutropenia. To classify common chronic neutropenia causes in a pediatric immunology unit. We enrolled 109 chronic neutropenia patients admitted to a pediatric immunology department between 2002-2022. We recorded clinical/laboratory features and genetic characteristics. The male/female ratio was 63/46. Fifty-eight patients had parental consanguinity(57.4%). 26.6% (n = 29) patients had at least one individual in their family with neutropenia. Common symtpoms at presentation were upper respiratory tract infections(URTI)(31.1%), oral aphthae(23.6%), skin infections(23.6%), pneumonia(20.8%), and recurrent abscesses(12.3%). Common infections during follow-up were URTI(56.8%), pneumonia(33%), skin infections(25.6%), gastroenteritis(18.3%), and recurrent abscesses(14,6%). Common long-term complications were dental problems(n = 51), osteoporosis(n = 22), growth retardation(n = 14), malignancy(n = 16)[myelodysplastic syndrome(n = 10), large granulocytic leukemia(n = 1), acute lymphoblastic leukemia(n = 1), Hodgkin lymphoma(n = 1), EBV-related lymphoma(n = 1), leiomyosarcoma(n = 1), and thyroid neoplasm(n = 1)]. We performed a genetic study in 86 patients, and 69(71%) got a genetic diagnosis. Common gene defects were HAX-1(n = 26), ELA-2 (ELANE)(n = 10), AP3B1(n = 4), and ADA-2(n = 4) gene defects. The IEI ratio(70.6%) was high. GCSF treatment(93.4%), immunoglobulin replacement therapy(18.7%), and HSCT(15.9%) were the treatment options. The mortality rate was 12.9%(n = 14). The most common long term complications were dental problems that is three times more common in patients with known genetic mutations. We prepared an algorithm for chronic neutropenia depending on the present cohort. An important rate of inborn errors of immunity, especially combined immunodeficiency(11.9%) was presented in addition to congenital phagocytic cell defects. Early diagnosis will allow us tailor the disease-specific treatment options sooner, preventing irreversible consequences., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose of Review: Atypical chemokine receptor-1 (ACKR1)/Duffy antigen receptor of chemokines (DARC)-associated neutropenia (ADAN; OMIM 611862), previously named benign ethnic neutropenia, and present in two-thirds of individuals identifying as Black in the USA, is associated with mild to moderate decreases in peripheral neutrophil counts that nevertheless do not lead to increased infections. Consequently, recent initiatives have sought to establish normal neutrophil count reference ranges for ADAN, considering it a normal variant rather than a clinical disorder requiring medical intervention., Recent Findings: A limited number of studies elucidating the mechanism of neutropenia in ADAN has suggested that neutrophils may redistribute from peripheral blood to the tissues including the spleen: this might explain why ADAN is not associated with increased risks of infection since the total number of neutrophils in the body remains normal. In this review, we critically examine the research underlying the molecular basis of ADAN., Summary: Insights into the biology of neutrophils and their trafficking may inform the clinical interpretation of neutropenia in ADAN. The bulk of research suggests that ADAN does not lead to a diminished host defense as do other forms of neutropenia. However, ADAN may lead to increased proinflammatory signaling, with possible implications for senescence of the immune system and predisposition to autoimmunity and cancer., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Chronic idiopathic neutropenia (CIN) is a rare benign condition  caused by an immune attack against neutrophils, either primary or in the context of other autoimmune conditions, lymphoproliferative syndromes, and inborn errors of immunity. In this single-center prospective study, 131 adult CIN patients were enrolled (median age 55 years, range: 20-93). At baseline, 56% had anti-neutrophil autoantibodies and 31% had autoimmune comorbidities. Over a median 3-year follow-up, the rate of grade ≥ 2 infections was 42%, with 10% grade ≥ 3, irrespective of neutrophil counts, demographics, and anti-neutrophil antibodies positivity, and G-CSF was used in 6 patients only. No malignant evolution nor deaths were observed. Bone marrow evaluation showed a large granular lymphocyte (LGL) infiltrate in 52%, mostly polyclonal, and hypocellularity in 31% of cases. Immune-histochemistry highlighted deposits of IgG, IgM, and complement fractions C3 and C4d in most cases. Interestingly, 19% of tested patients displayed somatic mutations of myeloid genes with an association with age. In conclusion, adult CIN appears to be a benign condition without life-threatening infections, yet deserving an extensive hematologic evaluation including bone marrow assessment to inform the differential diagnosis., (© 2024. The Author(s).)

Background Aims: The success of chimeric antigen receptor (CAR) T-cell therapy in treating B-cell malignancies has led to the evaluation of CAR T-cells targeting a variety of other malignancies. Although the efficacy of CAR T-cells is enhanced when administered post-lymphodepleting chemotherapy, this can trigger bone marrow suppression and sustained cytopenia after CD19.CAR T-cell therapy. Additionally, systemic inflammation associated with CAR T-cell activity may contribute to myelosuppression. Cytopenias, such as neutropenia and thrombocytopenia, elevate the risk of severe infections and bleeding, respectively. However, data on the incidence of prolonged cytopenias after immune effector therapy in the solid tumor context remain limited., Objective: We compared the incidence of prolonged cytopenias after immune effector therapy including genetically modified T-cells, virus-specific T-cells (VSTs) and NKT-cells, as well non-gene-modified VSTs for leukemia, lymphoma, and solid tumors (ST) to identify associated risk factors., Methods: A retrospective analysis was conducted of 112 pediatric and adult patients with relapsed and/or refractory cancers who received lymphodepleting chemotherapy followed by immune effector therapy. Patients treated with 13 distinct immune effector cell therapies through 11 single-center clinical trials and 2 commercial products over a 6-year period were categorized into 3 types of malignancies: leukemia, lymphoma and ST. We obtained baseline patient characteristics and adverse events data for each participant, and tracked neutrophil and platelet counts following lymphodepletion., Results: Of 112 patients, 104 (92.9%) experienced cytopenias and 88 (79%) experienced severe cytopenias. Patients with leukemia experienced significantly longer durations of severe neutropenia (median duration of 14 days) compared with patients with lymphoma (7 days) or ST (11 days) (P = 0.002). Patients with leukemia also had a higher incidence of severe thrombocytopenia (74.1%), compared with lymphoma (46%, P = 0.03) and ST (14.3%, P < 0.0001). Prolonged cytopenias were significantly associated with disease type (63% of patients with leukemia, 44% of patients with lymphoma, and 22.9% of patients with ST, P = 0.006), prior hematopoietic stem cell transplant (HSCT) (66.7% with prior HSCT versus 38.3% without prior HSCT, P = 0.039), and development of immune effector cell-associated neurotoxicity syndrome (ICANS) (75% with ICANS versus 38% without ICANS, P = 0.027). There was no significant association between prolonged cytopenias and cytokine release syndrome., Conclusions: Immune effector recipients often experience significant cytopenias due to marrow suppression following lymphodepletion regardless of disease, but prolonged severe cytopenias are significantly less common after treatment of patients with lymphoma and solid tumors., (Published by Elsevier Inc.)

Background: LCP1 encodes L-plastin, an actin-bundling protein primarily expressed in hematopoietic cells. In mouse and fish models, LCP1 deficiency has been shown to result in hematologic and immune defects., Objective: This study aimed to determine the nature of a human inborn error of immunity resulting from a novel genetic variant of LCP1., Methods: We performed genetic, protein, and cellular analysis of PBMCs from a kindred with apparent autosomal dominant immune deficiency. We identified a candidate causal mutation in LCP1, which we evaluated by engineering the orthologous mutation in mice and Jurkat cells., Results: A splice-site variant in LCP1 segregated with lymphopenia, neutropenia, and thrombocytopenia. The splicing defect resulted in at least 2 aberrant transcripts, producing an in-frame deletion of 24 nucleotides, and a frameshift deletion of exon 8. Cellular analysis of the kindred revealed a proportionate reduction of T and B cells and a mild expansion of transitional B cells. Similarly, mice carrying the orthologous genetic variant exhibited the same in-frame aberrant transcript, reduced expression Lcp1 and gene dose-dependent leukopenia, mild thrombocytopenia, and lymphopenia, with a significant reduction of T-cell populations. Functional analysis revealed that LCP1 c740 - 1G>A confers a defect in platelet development and function with aberrant spreading on collagen. Immunologic analysis revealed defective actin organization in T cells, reduced migration of PBMCs from patients, splenocytes from mutant mice, and a mutant Jurkat cell line in response to CXCL12; impaired germinal center B-cell expansion after immunization; and reduced cytokinesis during T cell proliferation., Conclusions: We describe a unique human hematopoietic defect affecting neutrophils, lymphocytes, and platelets arising from partial LCP1 deficiency., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: To evaluate the risk of neutropenia during treatment with anti-IL-23 antibodies in patients with psoriasis., Method: We conducted an observational study with cohort design using MID-NET ® in Japan. We identified patients with psoriasis who were newly prescribed anti-IL-23 antibodies, anti-IL-17-antibodies, adalimumab, or apremilast between January 1, 2009, and March 31, 2021. We estimated the adjusted hazard ratio (aHR) of anti-IL-23 antibodies compared to that of anti-IL-17 antibodies, adalimumab, or apremilast, for the risk of grade 2 (neutrophil count < 1,500/μL) or grade 3 (neutrophil count < 1,000/μL) neutropenia., Results: Overall, 287 patients on anti-IL-23 antibodies, 189 patients on anti-IL-17 antibodies, 293 patients on adalimumab, and 540 patients on apremilast were included. Compared with anti-IL-17 antibodies, the aHR (95% confidence interval (CI)) of anti-IL-23 antibodies was 0.83 (0.27-2.51) for grade 2 and 0.40 (0.02-7.60) for grade 3 neutropenia; that when compared with adalimumab was 0.76 (0.28-2.06) for grade 2 but was not calculated for grade 3 as no cases were found; and that compared with apremilast was 3.88 (0.62-24.48) for grade 2 and 0.43 (0.02-11.63) for grade 3 neutropenia., Conclusion: No clear increase in the risk of neutropenia with anti-IL-23 antibodies was observed.

Agammaglobulinemia represents the most profound primary antibody deficiency, stemming from early cessation of B-cell development. Deficiency in folliculin-interacting protein 1 (FNIP1) is a novel inborn error of immunity characterized by a severe defect in B-cell development, agammaglobulinemia, variable neutropenia, and hypertrophic cardiomyopathy. FNIP1 plays a critical role in B-cell development and metabolic homeostasis, establishing a metabolic checkpoint that ensures pre-B cells possess sufficient metabolic capacity to undergo division while concurrently limiting lymphogenesis due to abnormal growth. Disruption of FNIP1 functionality affects the fundamental metabolic regulators adenosine monophosphate-activated protein kinase and mTOR, culminating in a severe B-cell deficiency alongside hypogammaglobulinemia, hypertrophic cardiomyopathy, preexcitation syndrome, and intermittent neutropenia. This case report presents an 11-month-old male patient with FNIP1 deficiency who, in addition to classical features, exhibited posterior cerebellar hypoplasia., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Autoimmune neutropenia (AIN) in early childhood is characterized by chronic neutropenia and positivity for human neutrophil antibodies (HNA), resulting in the excessive destruction of neutrophils. The association between regulatory T cells (Tregs) and AIN has been described, and in this study, we investigated three Treg-associated genes, IL-2, IL-10 and FOXP3. The frequencies of three single nucleotide polymorphisms (SNPs) in IL-2 -330T>G (rs2069762), +114G>T (rs2069763) and IVS3-116 A>G (rs2069772), four SNPs in IL-10 -3575T>A (rs1800890), -1082G>A (rs1800896), -819 C>T (rs1800871) and -592 C>A (rs1800872) and three SNPs in FOXP3 -3499 A>G (rs3761547), -3279 C>A (rs3761548) and -924 A>G (rs2232365) were compared between 166 Danish AIN patients and 358 healthy controls. Disease association was observed for IL-2 IVS3-116 GG (p = 0.0081, OR = 0.35 [0.15-0.80]), IL-10 -3575 TT (p = 0.0078, OR = 1.71 [1.16-2.54]) and IL-10 -1082 AA (p = 0.014, OR = 1.76 [1.14-2.72]) in all patients and FOXP3 -924 (p = 0.0005, A OR = 0.41 [0.25-0.68] and G OR = 2.42 [1.46-4.01]) in male patients. None of the associations were linked to antibody specificity. Disease-associated haplotypes were observed in IL-2 and FOXP3. IL-2 -330T/+114 T/IVS3-116A was associated with anti-FcγRIIIb-positive patients (p = 0.012, OR = 2.07 [1.18-3.62]). FOXP3 -3499A/-3279C/-924A was associated with anti-HNA-1a-positive male patients (p = 0.016, OR = 0.41 [0.20-0.83]), and ACG was associated with female patients, both in the combined group (p = 0.006, OR = NA) and the anti-FcγRIIIb-positive group (p = 0.002, OR = NA). We conclude that our findings reveal a correlation between SNP in Treg-associated genes and AIN, indicating that AIN could be driven by dysfunction of immune homeostatic-evolving Tregs., (© 2024 The Authors. Scandinavian Journal of Immunology published by John Wiley & Sons Ltd on behalf of The Scandinavian Foundation for Immunology.)

Background and Objectives: The isolation of neutrophils and subsequent detection of anti-human neutrophil antigens (HNA) antibodies are crucial in clinical medicine for the diagnosis of autoimmune neutropenia, neonatal alloimmune neutropenia (NAIN) and transfusion-related acute lung injury (TRALI). This study reports two cases of maternal anti-Fc-gamma-receptor-IIIb (FcγRIIIb) isoimmunization without NAIN symptoms and compares the efficiency of immunomagnetic negative selection (IMNS) with traditional dextran/Ficoll for neutrophil isolation in HNA serological assays., Materials and Methods: Investigating two cases of maternal anti-FcγRIIIb isoimmunization, neutrophils from three donors were isolated from 8 mL of whole blood using IMNS and dextran/Ficoll. Serological assays included the granulocyte agglutination and immunofluorescence test, monoclonal antibody immobilization of granulocyte antigens and the LABScreen Multi (One Lambda). IMNS and dextran/Ficoll were compared in terms of cell yield, viability, time, cost and purity., Results: Maternal anti-FcγRIIIb isoantibodies with FCGR3B gene deletion were detected in both cases. Newborns and fathers exhibited specific gene combinations: FCGR3B*02/FCGR3B*02 (Case 1) and FCGR3B*02/FCGR3B*03 (Case 2). IMNS outperformed dextran/Ficoll, yielding four times more neutrophils (average neutrophil counts: 18.5 × 10 3 /μL vs. 4.5 × 10 3 /μL), efficiently removing non-neutrophil cells and reducing processing time (30-40 min vs. 70-90 min), although it incurred a higher cost (2.7 times)., Conclusion: Two cases of maternal anti-FcγRIIIb isoantibodies, unrelated to NAIN, were identified. Although neutropenia has not been described in these cases, we emphasize the importance of identifying asymptomatic cases with the potential for severe neutropenia. Additionally, IMNS is introduced as a rapid, high-yield, high-purity neutrophil isolation technique, beneficial for serological assays detecting anti-HNA antibodies., (© 2024 International Society of Blood Transfusion.)

Dengue, the most prevalent mosquito-borne disease worldwide, poses a significant health burden. This study integrates clinical data and transcriptomic datasets from different phases of dengue to investigate distinctive and shared cellular and molecular features. Clinical data from 29 dengue patients were collected and analyzed alongside a public transcriptomic data set (GSE28405) to perform differential gene expression analysis, functional enrichment, immune landscape assessment, and development of machine learning model. Neutropenia was observed in 54.79% of dengue patients, particularly during the defervescence phase (65.79%) in clinical cohorts. Bioinformatics analyses corroborated a significant reduction in neutrophil immune infiltration in dengue patients. Receiver operating characteristic curve analysis demonstrated that dynamic changes in neutrophil infiltration levels could predict disease progression, especially during the defervescence phase, with the area under the curve of 0.96. Three neutrophil-associated biomarkers-DHRS12, Transforming growth factor alpha, and ZDHHC19-were identified as promising for diagnosing and predicting dengue progression. In addition, the activation of neutrophil extracellular traps was significantly enhanced and linked to FcγR-mediated signaling pathways and Toll-like receptor signaling pathways. Neutrophil activation and depletion play a critical role in dengue's immune response. The identified biomarkers and their associated pathways offer potential for improved diagnosis and understanding of dengue pathogenesis and progression., (© 2024 Wiley Periodicals LLC.)

WHIM syndrome is an inherited immune disorder caused by an autosomal dominant heterozygous mutation in CXCR4. The disease is characterized by neutropenia/leukopenia (secondary to retention of mature neutrophils in bone marrow), recurrent bacterial infections, treatment-refractory warts, and hypogammaglobulinemia. All mutations reported in WHIM patients lead to the truncations in the C-terminal domain of CXCR4, R334X being the most frequent. This defect prevents receptor internalization and enhances both calcium mobilization and ERK phosphorylation, resulting in increased chemotaxis in response to the unique ligand CXCL12. Here, we describe 3 patients presenting neutropenia and myelokathexis, but normal lymphocyte count and immunoglobulin levels, carrying what we believe to be a novel Leu317fsX3 mutation in CXCR4, leading to a complete truncation of its intracellular tail. The analysis of the L317fsX3 mutation in cells derived from patients and in vitro cellular models reveals unique signaling features in comparison with R334X mutation. The L317fsX3 mutation impairs CXCR4 downregulation and β-arrestin recruitment in response to CXCL12 and reduces other signaling events - including ERK1/2 phosphorylation, calcium mobilization, and chemotaxis - all processes that are typically enhanced in cells carrying the R334X mutation. Our findings suggest that, overall, the L317fsX3 mutation may be causative of a form of WHIM syndrome not associated with an augmented CXCR4 response to CXCL12.

Case presentation: A 72-year-old man with non-small-cell lung cancer received four cycles of pembrolizumab-containing chemotherapy. He developed multiple immune-related adverse events (irAEs) and discontinued immune checkpoint inhibitors (ICIs); however, he developed immune-related hepatitis and grade 4 neutropenia at 92 days and 118 days, respectively, from discontinuation. He received G-CSF and methylprednisolone pulse therapy and recovered from neutropenia 12 days later. Discussion & conclusion: ICI-induced neutropenia is a life-threatening condition. The longest recorded onset in one study cohort is 26 days after the final administration of ICIs. This case developed strikingly delayed immune-related neutropenia manifesting as a delayed irAE. Clinicians should pay close attention to delayed immune-related neutropenia as a possible life-threatening irAE after ICI treatment.

We report on the presentation and outcome of a 28-year-old female who developed red cell aplasia following alemtuzumab therapy for relapsing remitting multiple sclerosis. The patient also developed synchronous immune thrombocytopenia and immune neutropenia, but not aplastic anemia. This patient received high dose steroids, intravenous immunoglobulin (iv.Ig), rituximab, red cell transfusions, vincristine, G-CSF, cyclosporin and mycophenolate to treat the combination of cytopenias over a period of 6 months with subsequent improvement in bone marrow function. While alemtuzumab has several recognized autoimmune complications, little is known about the potential hematological side effects. The combination of red cell aplasia, immune thrombocytic purpura and autoimmune neutropenia has not previously been described in the literature following alemtuzumab immunotherapy and highlights the importance of monthly blood monitoring post alemtuzumab administration.

As a key member of the innate and adaptive immune response, neutrophils provide insights into the hematopoietic and inflammatory manifestations of inborn errors of immunity (IEI) and the consequences of immunotherapy. The facile recognition of IEI presenting with neutropenia provides an avenue for hematologists to facilitate early diagnosis and expedite biologically rationale care. Moreover, enhancing the understanding of the molecular mechanisms driving neutropenia in IEI-decreased bone marrow reserves, diminished egress from the bone marrow, and decreased survival-offers an opportunity to further dissect the pathophysiology driving neutropenia secondary to iatrogenic immune dysregulation, eg, immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy., (Copyright © 2021 by The American Society of Hematology.)

Autoimmune neutropenia is a type of immune-mediated neutropenia, caused by antibody-induced neutrophil destruction. Here we report two cases (3-year-old boy and 9-year-old girl) with suspected autoimmune neutropenia. The presence of neutrophil antibodies in sera of these patients was investigated using standard neutrophil antibody screening tests such as granulocyte immunofluorescence test (GIFT), granulocyte agglutination test (GAT), and lymphocyte immunofluorescence test (LIFT). A positive reactivity with two panel cells was found in GIFT. No reactivities with panel cells were observed in GAT and LIFT. To the best of our knowledge, this is the first report for detecting the neutrophil reactive antibodies using genotyped neutrophils in patients with autoimmune neutropenia in Iran. The final diagnosis of our patients was primary autoimmune neutropenia for the boy and autoimmune neutropenia associated with familial Mediterranean fever for the girl.

Chimeric antigen receptor (CAR) T cells are a new class of anti-cancer therapy that involves manipulating autologous or allogeneic T cells to express a CAR directed against a membrane antigen. In Europe, tisagenlecleucel (Kymriah™) has marketing authorization for the treatment of relapsed / refractory acute lymphoblastic leukemia (ALL) in children and young adults, in addition to the treatment of relapsed/refractory diffuse large B-cell lymphoma (DLBCL); the marketing authorization for axicabtagene ciloleucel (Yescarta™) is for the treatment of relapsed / refractory high-grade B-cell lymphoma and for the treatment of primary mediastinal B-cell lymphoma. Both cell products are genetically modified autologous T cells directed against CD19. These recommendations, drawn up by a working group of the Francophone Society of Bone Marrow transplantation and cellular Therapy (SFGM-TC) relate to the management of patients and the supply chain: medium-term complications, in particular cytopenias and B-cell aplasia, nursing and psychological supportive care. In another work, we will address long-term monitoring, post-marketing authorization pharmacovigilance and issues relating to JACIE and regulatory authorities. These recommendations are not prescriptive; their aim is to provide guidelines for the use of this new therapeutic approach. The purpose of this workshop is to outline the organizational aspects of this new therapeutic approach., (Copyright © 2021 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.)

Large granular lymphocyte leukemia (LGLL) is a rare lymphoproliferative disorder characterized by the clonal expansion of cytotoxic T-LGL or NK cells. Chronic isolated neutropenia represents the clinical hallmark of the disease, being present in up to 80% of cases. New advances were made in the biological characterization of neutropenia in these patients, in particular STAT3 mutations and a discrete immunophenotype are now recognized as relevant features. Nevertheless, the etiology of LGLL-related neutropenia is not completely elucidated and several mechanisms, including humoral abnormalities, bone marrow infiltration/substitution and cell-mediated cytotoxicity might cooperate to its pathogenesis. As a consequence of the multifactorial nature of LGLL-related neutropenia, a targeted therapeutic approach for neutropenic patients has not been developed yet; moreover, specific guidelines based on prospective trials are still lacking, thus making the treatment of this disorder a complex and challenging task. Immunosuppressive therapy represents the current, although poorly effective, therapeutic strategy. The recent identification of a STAT3-mediated miR-146b down-regulation in neutropenic T-LGLL patients emphasized the pathogenetic role of STAT3 activation in neutropenia development. Accordingly, JAK/STAT3 axis inhibition and miR-146b restoration might represent tempting strategies and should be prospectively evaluated for the treatment of neutropenic LGLL patients.

Neutrophils are essential to control several fungal infections. These cells are commonly known for their pro-inflammatory activities. However, some studies have demonstrated the anti-inflammatory properties of neutrophils during certain infectious diseases, culminating in the inhibition of T cell proliferation. Chromoblastomycosis (CBM) is a deep and progressive mycosis that affects thousands of people worldwide. Although neutrophil infiltrates are observed in the lesion histopathology, the fungus can overtake the immune system response and destroy the host-infected tissue. The present study demonstrated that neutropenic animals had an increase in the IL-6 production in the spleen and liver, followed by a lower fungal burden in these organs up to 14 days of infection. Neutropenic animals also showed a lower F. pedrosoi-specific antibody production 14-days post infection and higher T-cell proliferation in the in vitro experiments after stimulation with F. pedrosoi-purified proteins. Taken together, our results suggest that the presence of regulatory neutrophils in the mouse model of F. pedrosoi infection could act favoring the spread of the fungus and the chronicity of the infection. These findings shed light on the CBM treatment, which might target neutrophil polarization as a new therapy approach to treat CBM lesions., (© 2021. The Author(s).)

Avadomide is a cereblon E3 ligase modulator and a potent antitumor and immunomodulatory agent. Avadomide trials are challenged by neutropenia as a major adverse event and a dose-limiting toxicity. Intermittent dosing schedules supported by preclinical data provide a strategy to reduce frequency and severity of neutropenia; however, the identification of optimal dosing schedules remains a clinical challenge. Quantitative systems pharmacology (QSP) modeling offers opportunities for virtual screening of efficacy and toxicity levels produced by alternative dose and schedule regimens, thereby supporting decision-making in translational drug development. We formulated a QSP model to capture the mechanism of avadomide-induced neutropenia, which involves cereblon-mediated degradation of transcription factor Ikaros, resulting in a maturation block of the neutrophil lineage. The neutropenia model was integrated with avadomide-specific pharmacokinetic and pharmacodynamic models to capture dose-dependent effects. Additionally, we generated a disease-specific virtual patient population to represent the variability in patient characteristics and response to treatment observed for a diffuse large B-cell lymphoma trial cohort. Model utility was demonstrated by simulating the avadomide effect in the virtual population for various dosing schedules and determining the incidence of high-grade neutropenia, its duration, and the probability of recovery to low-grade neutropenia., (© 2021. The Author(s).)

Introduction: Inherited phagocyte defects are one of the subgroups of primary immunodeficiency diseases (PIDs) with various clinical manifestations. As oral manifestations are common at the early ages, oral practitioners can have a special role in the early diagnosis., Materials and Methods: A comprehensive search was conducted in this systematic review study and data of included studies were categorized into four subgroups of phagocyte defects, including congenital neutropenia, defects of motility, defects of respiratory burst, and other non-lymphoid defects., Results: Among all phagocyte defects, 12 disorders had reported data for oral manifestations in published articles. A total of 987 cases were included in this study. Periodontitis is one of the most common oral manifestations., Conclusion: There is a need to organize better collaboration between medical doctors and dentists to diagnose and treat patients with phagocyte defects. Regular dental visits and professional oral health care are recommended from the time of the first primary teeth eruption in newborns., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: SCN4 is an autosomal recessive disease caused by mutations in the G6PC3 gene. The clinical, molecular, and immunological features; function of neutrophils; and prognosis of patients with SCN4 have not been fully elucidated., Methods: Two Chinese pediatric patients with G6PC3 mutations were enrolled in this study. Clinical data, genetic and immunologic characteristics, and neutrophil function were evaluated in patients and controls before and after granulocyte colony-stimulating factor (G-CSF) treatment., Results: Both patients had histories of pneumonia, inguinal hernia, cryptorchidism, and recurrent oral ulcers. Patient 1 also had asthma and otitis media, and patient 2 presented with prominent ectatic superficial veins and inflammatory bowel disease. DNA sequencing demonstrated that both patients harbored heterozygous G6PC3 gene mutations. Spontaneous and FAS-induced neutrophil apoptosis were significantly increased in patients, and improved only slightly after G-CSF treatment, while neutrophil respiratory burst and neutrophil extracellular traps production remained impaired in patients after G-CSF treatment., Conclusion: G-CSF treatment is insufficient for patients with SCN4 patients, who remain at risk of infection. Where possible, regular G-CSF treatment, long-term prevention of infection, are the optimal methods for cure of SCN4 patients. It is important to monitor closely for signs of leukemia in SCN4 patients. Once leukemia occurs in SCN4 patients, hematopoietic stem cell transplantation is the most important choice of treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Dai, Lv, Li, Tang, Chen, Liu, Yang, Zhang, Tian, Zhou, Yan, Wang, Ding, An, Zhang, Tang and Zhao.)

Standard therapy in hairy cell leukemia (HCL) is often impossible at the time of deep neutropenia/agranulocytosis with or without infectious complications; it is thus a complex therapeutic problem. Vemurafenib has been used to treat resistant HCL since 2012. Because vemurafenib does not have a myelotoxic effect, we thought that it could be used to treat HCL associated with deep neutropenia/agranulocytosis with or without the development of infectious complications as a preliminary stage before treatment with cladribine. We conducted a retrospective analysis of treatment with vemurafenib followed by a standard course of cladribine provided to 22 patients with deep neutropenia/agranulocytosis with or without infectious complications at diagnosis. Vemurafenib was provided to 22 patients with HCL. The response to therapy was evaluated by complete blood cell count (absolute neutrophil count [ANC], hemoglobin concentration, platelet count, absence of hairy cells), spleen size (assessed by ultrasound), and reduce infectious complications. After that, a standard course of cladribine was provided. Among the 22 patients, the male/female sex ratio was 2:1, and median (range) age was 52 (24-78) years. There were 7 patients with severe infectious manifestations admitted to the intensive care unit, including 1 patient during extracorporeal membrane oxygenation. The median (range) ANC at diagnosis was 0.3 (0.04-0.7) × 10 9 /L. Vemurafenib was provided at a dosage of 240 mg 1 or 2 times a day. In 20 patients, vemurafenib was provided for 3 months or more. In 1 case, the effect was not obtained during 1 month of treatment, and the patient died from severe infectious complications during prolonged agranulocytosis. In 21 patients treated with vemurafenib, an increase of ANC was observed and the infectious complications resolved, thus allowing the application of cladribine therapy. After a standard course (0.1 mg/kg per day for 7 days) of cladribine chemotherapy, 18 patients (90%) experienced complete clinical remission and 2 patients (10%) experienced partial remission with residual splenomegaly. In 1 patient, vemurafenib therapy was still ongoing 2 months after initiating therapy. In cases of proven BRAF V600E mutation, vemurafenib can be successfully used as an effective preliminary therapy in patients with deep neutropenia/agranulocytosis with or without infectious complications before standard therapy with purine analogs., (Copyright © 2021 Elsevier Inc. All rights reserved.)

While umbilical cord blood is increasingly utilized as a stem cell source, immune complications associated with the procedure have been recognized. These complications result from significant immune system dysregulation and defective reconstitution following transplant causing an imbalance between T-cell subsets, aberrant B cells, and abnormal antibody production. This may occur up to 12 months after transplant coinciding with thymic regeneration in adults. The aim of our review is to describe the incidence, pathophysiology, clinical features, and prognosis of autoimmune cytopenias following umbilical cord blood transplant. Furthermore, we review the treatment strategies reported in the existing literature, describe the authors' experience with the complication, and highlight novel treatment options being studied. The knowledge of the occurrence and timing of autoimmune complications of umbilical cord blood transplantation is essential for detection and treatment of the disease. Emerging therapeutic options include interleukin-2 (IL-2), which is also being studied for the treatment of acute and chronic graft-versus-host disease. IL-2 has favorable effects on growth, differentiation, and function of regulatory T cells. Monoclonal antibody treatments, such as daratumumab, are also on the forefront and more experience with them will guide further treatment strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.)

Background: CD177 is a surface protein on neutrophils and a main mediator for the surface expression of proteinase 3 (PR3). Its functions are largely unknown. At least three types of antibodies have been described to target CD177: isoantibodies, which are formed in CD177-null individuals as a result of an immune reaction following transfusion or pregnancy; autoantibodies present in sera from patients with autoimmune neutropenia; and antineutrophil cytoplasmic antibodies in sera from patients with glomerulonephritis with polyangiitis. In this study, we aimed to compare the binding characteristics of auto- and iso-antibodies to optimize their detectability in the neutrophil serology laboratory., Study Design and Methods: The reactivity of iso- and auto-antibodies against CD177 was studied using granulocytes, "native" CD177/PR3 complex, and recombinant CD177 or PR3., Results: All iso- and auto-antibodies were reactive with CD177/PR3 when immobilized with monoclonal antibody (moab) 7D8. Seventy-five percent of autoantibodies, but none of the isoantibodies, did not react with CD177/PR3 immobilized with moab MEM166. The majority of autoantibodies did not react with recombinant CD177, whereas most isoantibodies tested positive., Discussion: Our results suggest that iso- and auto-antibodies against CD177 target different epitopes. Isoantibodies mainly target CD177 alone, while the majority of autoantibodies target a native epitope present on the neutrophil surface, but absent from recombinant CD177 which lacks PR3. Moab MEM166 binds to the native epitope and hinders the binding of CD177 autoantibodies. The results may help to design diagnostic strategies, especially for the identification of autoantibodies., (© 2021 The Authors. Transfusion published by Wiley Periodicals LLC. on behalf of AABB.)

Descriptions of passenger lymphocyte syndrome (PLS), immune cytopenias and transplant-associated thrombotic microangiopathy (TA-TMA) after intestine-containing transplants remain scarce. We describe our centre's experience of these complications from 2007 to 2019. Ninety-six patients received 103 transplants. PLS occurred in 9 (9%) patients (median 12 days post-transplant); all due to ABO antibodies. There were 31 minor ABO mismatch transplants. No patient required change in immunosuppression. Immune cytopenias (excluding PLS) occurred in six patients at an incidence of 1·7/100 patient years; three immune haemolysis, one immune thrombocytopenia, one acquired Glanzmann's and one immune neutropenia; 50% occurred with other cytopenias. All cases eventually responded to treatment, with a median of four treatments (range 1-8) and 5/6 were treated with rituximab. One patient with immune haemolysis required bortezomib. Complications were common in patients with immune cytopenias; 4/6 with infection needing intravenous antibiotics and 3/6 with venous thromboembolism. In 3/6 cases, a secondary cause for the immune cytopenia was evident. Switching from tacrolimus to ciclosporin was not necessary. There were five cases of transplant-associated thrombotic microangiopathy (TA-TMA; 1·5/100 patient years) requiring calcineurin inhibitor withdrawal; two cases associated with acute rejection. Two cases were managed with plasma exchange, one with plasma infusions and one with eculizumab. Further research in this patient group is required., (© 2021 British Society for Haematology and John Wiley & Sons Ltd.)

Rituximab is an antibody that binds to B-lymphocytes and is increasingly used during pregnancy. As an immunoglobulin G, it will transfer across the placenta. Previous case reports describe a diversity of clinical presentations in neonates born following rituximab exposure in utero. Our case is the first to offer the long-term experience in the care of an infant with severe neutropenia and prolonged profound hypogammaglobulinemia and class-switching B cell defect after in utero rituximab exposure., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Granulocytes are an essential part of both the innate and adaptive immune systems. Human neutrophil antigens (HNAs) are a family of epitopes that are located on glycoproteins that are mostly expressed on human granulocytes. Antibodies that recognize these epitopes have been associated with neutropenia, transfusion complications, haematopoietic stem cell transplant nonengraftment and renal transplant rejection. Currently, there are fourteen recognized HNA alleles across five antigen systems (HNA-1 through HNA-5), the molecular basis of which are located on the genes FCGR3B, CD177, SLC44A2, ITGAM and ITGAL, respectively. Elucidation of the associated genes has permitted the development of testing strategies for HNA typing and aided understanding of the associated epitopes. This review will outline the associated clinical conditions that require HNA investigation and how these are performed in specialized laboratories. Investigations provided are both reactive for patients with a variety of existing or suspected neutropenias and proactive in the testing of blood component donors in order to reduce the potential risk to patients who require transfusion., (© 2020 John Wiley & Sons Ltd.)

Introduction: With the increasing use of checkpoint inhibitors, rare immune-related adverse events (irAE) are being identified. Haematological irAE (hem-irAE) are difficult to treat and have shown high mortality rates. In order to improve side-effect management for these potentially life-threatening events, we analysed frequency, severity and outcomes., Patients and Methods: Patients who developed hem-irAE while being treated with immune checkpoint inhibitors (ICI) therapy were retrospectively identified from 18 international cancer centres., Results: In total, more than 7626 patients treated with ICI were screened, and 50 patients with hem-irAE identified. The calculated incidence amounts to 0.6% and median onset was 6 weeks after the ICI initiation (range 1-128 weeks). Thrombocytopenia and leucopaenia were the most frequent hem-irAE with 34% (17/50) and 34% (17/50), respectively, followed by anaemia 28% (14/50), hemophagocytic lymphohistiocytosis (4% (2/50)), aplastic anaemia (2% (1/50)), acquired haemophilia A (2% (1/50)) and coagulation deficiency (2% (1/50)). Simultaneous thrombocytopenia and neutropenia occurred in two patients, concurrent anaemia and thrombocytopenia in one patient. Other than cessation of ICI (in 60%) and corticosteroids (in 78%), treatment included second-line immunosuppression in 24% of cases. Events resolved in 78% (39/50), while 18% (9/50) had persistent changes, and 2% (1/50) had fatal outcomes (agranulocytosis)., Conclusion: Hem-irAE can affect all haematopoietic blood cell lineages and may persist or even be fatal. Management may require immunosuppression beyond corticosteroids. Although these irAE are rare, treating physicians should be aware, monitor blood counts regularly and promptly act upon detection., Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships, which may be considered as potential competing interests: Rafaela Kramer: NoneZaremba Anne: Received travel support from Novartis, Genzyme and Bristol-Myers Squibb. Alvaro Moreira: Speaker's honoraria from AbbVie, Novartis, Bristol-Myers Squibb, Pfizer and Roche; consultant's honoraria from Almirall. Selma Ugurel: Selma Ugurel declares research support from Bristol Myers Squibb and Merck Serono; speakers and advisory board honoraria from Bristol Myers Squibb, Merck Sharp and Dohme, Merck Serono, Novartis and Roche, and travel support from Bristol Myers Squibb, and Merck Sharp and Dohme. Douglas Johnson: Advisory boards for Array Biopharma, BMS, Catalyst, Iovance, Jansen, Merck, Novartis, and research funding from BMS and Incyte. Jessica C. Hassel: honoraria from BMS, MSD, Roche, Novartis, Pfizer, Sanofi; consultant's honoraria from Pierre Faber, MSD, Sunpharma; science grant from BMS. Martin Salzmann: honoraria and travel grants from Abbvie, Bristol-Myers Squibb (BMS), Merck, Merck Sharp & Dohme (MSD), Novartis and Pfizer. Anja Gesierich: speaker's honoraria from Bristol-Myers Squibb, MSD Sharp and Dohme and Roche; Consultant's honoraria from Amgen, Bristol-Myers Squibb, Novartis, MSD Sharp and Dohme, Pierre Fabre Pharmaceuticals, Pfizer, Roche and Sanofi Genzyme; travel support from Bristol-Myers Squibb, MSD Sharp and Dohme, Novartis, Pierre Fabre Pharmaceuticals and Roche. Clinical studies: Amgen, Array, Bristol-Myers Squibb, GSK, Novartis, Merck, MSD Sharp and Dohme, Pfizer and Roche. Alisonn Weppler: none. Lavinia Spain: Honoraria from Bristol-Myers Squibb for Advisory Boards Carmen Loquai: Advisory board, speakers fee, travel reimbursement: Roche, Pierre Fabre, Novartis, BMS, Merck, MSD, Biontech, Almiral Hermal, Kyowa Kirin, Sun Pharma, Sanofi Milena Dudda: none. Claudia Pföhler: Consultancy, speaker fees, travel grants: BMS, MSD, Merck, Roche, Amgen, GSK, Novartis, Sanofi Genzyme, Pierre Fabre, LEO. Clinical studies: Novartis, BMS. Adriana Hepner: AH is employee of AstraZeneca with stock options in the company, has received honoraria from Novartis and travel expenses from Roche. Georgina V. Long: consultant advisor for Aduro Biotech Inc, Amgen Inc, Array Biopharma inc, Boehringer Ingelheim International GmbH, Bristol-Myers Squibb, Highlight Therapeutics S.L., Merck Sharpe and Dohme, Novartis Pharma AG, QBiotics Group Limited, Regeneron Pharmaceuticals Inc, SkylineDX B.V. Alexander Menzies: advisory board BMS, MSD, Novartis, Roche, Pierre-Fabre, QBiotics Matteo S. Carlino: MSC has served on advisory boards for Bristol-Myers Squibb, MSD, Amgen, Novartis, Pierre Fabre, Roche, Sanofi, Merck, Ideaya, Regeneron, Nektar, Eisai and honoraria from Bristol-Myers Squibb, MSD, Novartis Michael M. Sachse: Speaker fees: Roche, MSD, Novartis Céleste Lebbé: Consultancy, speaker fees, travel grants or research funding: BMS, MSD, Merck, Roche, Amgen, Novartis, Sanofi, Pierre Fabre. Clinical studies: BMS, MSD, Merck, Sanofi, Incyrte, Roche, Amgen, GSK, Curevac, Genentech and Novartis Barouyr Baroudjian: Consultancy, speaker fees, travel grants: BMS, MSD, Novartis, Pierre Fabre Tomohiro Enokida: none. Makoto Tahara: reports grants and personal fees from Ono Pharmaceutical, grants and personal fees from MSD, grants and personal fees from BMS, during the conduct of the study; grants and personal fees from Bayer, grants and personal fees from Eisai, grants and personal fees from Merck serono, personal fees from LOXO, grants and personal fees from Pfizer, grants and personal fees from Rakuten Medical, personal fees from Celgene, personal fees from Amgen, grants and personal fees from Novartis, outside the submitted work. Max Schlaak: Consultancy, speaker fees or travel grants: BMS, MSD, Roche, Kyowa Kirin, Novartis, Sanofi Genzyme, Pierre Fabre, Sun Pharma Kinan Hayani: none. Paul Bröckelmann: PJB declares honoraria and non-financial support by Bristol-Myers Squibb and research funding by Bristol-Myers Squibb and MSD Sharp and Dohme. Friedegund Meier: F.M. has received travel support or/and speaker’s fees or/and advisor’s honoraria by Novartis, Roche, BMS, MSD and Pierre Fabre and research funding from Novartis and Roche. Lydia Reinhardt: none. Philip Friedlander: none. Thomas Eigentler: received fees for advisory boards from Roche, Novartis, MSD, BMS, Sanofi and Philogen Katharina C. Kähler: serves as consultant to Roche, BMS, MSD, Pierre Fabre and received travel grants and speaker fees from Roche, BMS, MSD, Amgen, Pierre Fabre and Philogen. Lisa Zimmer: LZ has received honoraria from Roche, Bristol-Myers Squibb, Merck Sharp and Dohme, Novartis, Pierre Fabre, research funding from Novartis and has served on advisory boards for Bristol-Myers Squibb, Novartis, Pierre Fabre, Sunpharma, Sanofi, Merck Sharp and Dohme; travel support: Bristol-Myers Squibb, Pierre Fabre, Sanofi, Amgen, Novartis, Sunpharma Lucie Heinzerling: Consultancy, speaker fees, travel grants or research funding: BMS, MSD, Merck, Roche, Amgen, Curevac, Novartis, Sanofi, Pierre Fabre. Clinical studies: BMS, MSD, Merck, Roche, Amgen, GSK, Curevac and Novartis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Autoimmune neutropenia (AIN) in childhood is characterized by chronic neutropenia and positivity for anti-neutrophil antibodies, resulting in the excessive destruction of neutrophils. In this study, we investigated the involvement of regulatory T cells (T regs ) in the pathogenesis of AIN in childhood. T regs have been classified into three subpopulations based on the expressions of CD45RA and forkhead box protein 3 (FoxP3): resting T regs , activated T regs and non-suppressive T regs . The frequency of activated T regs (CD4 + CD25 + FoxP3 high CD45RA - T cells) as well as that of total T regs (CD4 + CD25 + FoxP3 + T cells) in peripheral blood was significantly decreased in patients with AIN. Analysis of the T cell receptor (TCR)-Vβ repertoire of CD4 + T cells revealed skewed usages in patients with AIN compared with that observed in age-matched control subjects. Regarding T cell subsets, the use of four of 24 TCR-Vβ families in T regs and one in conventional T cells were increased in patients with AIN. The number of patients with AIN who showed skewed usages of TCR-Vβ family in conventional and T regs was significantly higher than that reported in control subjects. When the preference between T regs and conventional T cells in each TCR-Vβ family was individually compared, different use was prominently observed in the TCR-Vβ 9 family in patients with AIN. These results suggest that the quantitative abnormalities of T regs and the skew of the TCR-Vβ repertoire in CD4 + T cells, including T regs and conventional T cells, may be related to autoantibody production through a human neutrophil antigen-reactive T cell clone., (© 2020 British Society for Immunology.)

Acute lymphoblastic leukemia (ALL) typically responds better when treated with multiagent chemotherapy in the pediatric and young adolescent populations. Treatment of relapsed/refractory (RR) ALL remains a challenge. Even after stem-cell transplantation and intensive chemotherapy, the prognosis of RR-ALL remains grave. The advent of chimeric antigen receptors has demonstrated promising results in RR-ALL. Chimeric antigen receptor-modified T cells (CAR-T) and engineered T cells are used to target cancer cells. In 2017, the US Food and Drug Administration approved CD19-specific CAR-T (tisagenlecleucel) therapy for RR-B-cell ALL in patients under 25 years old. In this systematic review, we discuss the efficacy and safety of CD19-specific CAR-T therapy in RR-B-cell ALL in the pediatric and young adult population. We searched the PubMed, Embase, Web of Science, Cochrane Library, and clinical trials databases. A total of 448 patients received a CD19-specific CAR-T product, and 446 patients had evaluable data. The age range was 0 to 30 years. The incidence rate of complete remission was 82%. The cumulative incidence of relapse after CD19-specific CAR-T therapy is 36%. Similarly, the incidence rate of grade 3 or higher adverse events of neutropenia, thrombocytopenia, neurotoxicity, infections, and cytokine release syndrome were 38%, 23%, 18%, 29%, and 19%, respectively. Our subgroup analysis shows the incidence rate of minimal residual negative complete remission was 69% with the CD28z costimulatory domain, 81% with the 4-1BB domain, and 77% with fourth-generation CD19-specific CAR-T therapy., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The tumor microenvironment profoundly influences the behavior of recruited leukocytes and tissue-resident immune cells. These immune cells, which inherently have environmentally driven plasticity necessary for their roles in tissue homeostasis, dynamically interact with tumor cells and the tumor stroma and play critical roles in determining the course of disease. Among these immune cells, neutrophils were once considered much more static within the tumor microenvironment; however, some of these earlier assumptions were the product of the notorious difficulty in manipulating neutrophils in vitro. Technological advances that allow us to study neutrophils in context are now revealing the true roles of neutrophils in the tumor microenvironment. Here we discuss recent data generated by some of these tools and how these data might be synthesized into more elegant ways of targeting these powerful and abundant effector immune cells in the clinic.

The incidence of neutropenia and the association between neutropenia and severity of respiratory symptoms among infants with respiratory syncytial virus (RSV) infections remain to be elucidated. This single-center, retrospective study included immunocompetent infants (<10 months old) with laboratory-confirmed RSV infection admitted to our center between January 2012 and December 2019. Incidence of neutropenia (<1.0 × 10 9 /L) within 10 days of onset and risk factors associated with subsequent neutropenia were evaluated. Among the 292 infants with RSV infection, including 232 (79%) with mild infection, neutropenia was observed in 31 (11%), with severe neutropenia (<0.5 × 10 9 /L) in 3 (1.0%). No neutropenic infants developed serious infection or hematological disorder. Infants without neutropenia showed age <3 months at onset in 34%, C-reactive protein level <1.0 mg/L in 27%, and nasopharyngeal microbiota composition with any of Moraxella catarrhalis , Streptococcus pneumoniae , or Haemophilus influenzae in 63%. In comparison, infants with neutropenia showed age <3 months at onset in 74% (relative risk [RR] 2.15; 95% confidence interval [CI] 1.65-2.81), C-reactive protein level <1.0 mg/L in 55% (RR 2.02; 95% CI 1.38-2.94), and microbiota including Moraxella catarrhalis , Streptococcus pneumoniae , or Haemophilus influenzae in 15% (RR 0.24; 95% CI 0.10-0.61). Multiple logistic regression analyses showed that younger age at onset and absence of that nasopharyngeal microbiota profile were associated with development of neutropenia. In conclusion, age and airway microbiota are considered as risk factors for the development of transient neutropenia among infants with RSV infection. However, the neutropenia seems not to develop serious infection or hematological disorder.

Background: Bacterial meningitis is a fatal disease with a mortality up to 30% and neurological sequelae in one fourth of survivors. Available vaccines do not fully protect against this lethal disease. Here, we report the protective effect of synthetic oligodeoxynucleotides containing unmethylated cytosine-guanine motifs (CpG ODN) against the most frequent form of bacterial meningitis caused by Streptococcus pneumoniae., Methods: Three days prior to the induction of meningitis by intracerebral injection of S. pneumoniae D39, wild-type and Toll-like receptor (TLR9) -/- mice received an intraperitoneal injection of 100 μg CpG ODN or vehicle. To render mice neutropenic, anti-Ly-6G monoclonal antibody was daily administrated starting 4 days before infection with a total of 7 injections. Kaplan-Meier survival analyses and bacteriological studies, in which mice were sacrificed 24 h and 36 h after infection, were performed., Results: Pre-treatment with 100 μg CpG ODN prolonged survival of immunocompetent and neutropenic wild-type mice but not of TLR9 -/- mice. There was a trend towards lower mortality in CpG ODN-treated immunocompetent and neutropenic wild-type mice. CpG ODN caused an increase of IL-12/IL-23p40 levels in the spleen and serum in uninfected animals. The effects of CpG ODN on bacterial concentrations and development of clinical symptoms were associated with an increased number of microglia in the CNS during the early phase of infection. Elevated concentrations of IL-12/IL-23p40 and MIP-1α correlated with lower bacterial concentrations in the blood and spleen during infection., Conclusions: Pre-conditioning with CpG ODN strengthened the resistance of neutropenic and immunocompetent mice against S. pneumoniae meningitis in the presence of TLR9. Administration of CpG ODN decreased bacterial burden in the cerebellum and reduced the degree of bacteremia. Systemic administration of CpG ODN may help to prevent or slow the progression to sepsis of bacterial CNS infections in healthy and immunocompromised individuals even after direct inoculation of bacteria into the intracranial compartments, which can occur after sinusitis, mastoiditis, open head trauma, and surgery, including placement of an external ventricular drain.

Although IKK-β has previously been shown as a negative regulator of IL-1β secretion in mice, this role has not been proven in humans. Genetic studies of NF-κB signaling in humans with inherited diseases of the immune system have not demonstrated the relevance of the NF-κB pathway in suppressing IL-1β expression. Here, we report an infant with a clinical pathology comprising neutrophil-mediated autoinflammation and recurrent bacterial infections. Whole-exome sequencing revealed a de novo heterozygous missense mutation of NFKBIA, resulting in a L34P IκBα variant that severely repressed NF-κB activation and downstream cytokine production. Paradoxically, IL-1β secretion was elevated in the patient's stimulated leukocytes, in her induced pluripotent stem cell-derived macrophages, and in murine bone marrow-derived macrophages containing the L34P mutation. The patient's hypersecretion of IL-1β correlated with activated neutrophilia and liver fibrosis with neutrophil accumulation. Hematopoietic stem cell transplantation reversed neutrophilia, restored a resting state in neutrophils, and normalized IL-1β release from stimulated leukocytes. Additional therapeutic blockade of IL-1 ameliorated liver damage, while decreasing neutrophil activation and associated IL-1β secretion. Our studies reveal a previously unrecognized role of human IκBα as an essential regulator of canonical NF-κB signaling in the prevention of neutrophil-dependent autoinflammatory diseases. These findings also highlight the therapeutic potential of IL-1 inhibitors in treating complications arising from systemic NF-κB inhibition.

The role of neutrophils in solid tumor metastasis remains largely controversial. In preclinical models of solid tumors, both pro-metastatic and anti-metastatic effects of neutrophils have been reported. In this study, using mouse models of breast cancer, we demonstrate that the metastasis-modulating effects of neutrophils are dictated by the status of host natural killer (NK) cells. In NK cell-deficient mice, granulocyte colony-stimulating factor-expanded neutrophils show an inhibitory effect on the metastatic colonization of breast tumor cells in the lung. In contrast, in NK cell-competent mice, neutrophils facilitate metastatic colonization in the same tumor models. In an ex vivo neutrophil-NK cell-tumor cell tri-cell co-culture system, neutrophils are shown to potentially suppress the tumoricidal activity of NK cells, while neutrophils themselves are tumoricidal. Intriguingly, these two modulatory effects by neutrophils are both mediated by reactive oxygen species. Collectively, the absence or presence of NK cells, governs the net tumor-modulatory effects of neutrophils.

The field of primary immunodeficiencies (PIDs) is rapidly evolving. Indeed, the number of described diseases is constantly increasing thanks to the rapid identification of novel genetic defects by next-generation sequencing. PIDs are now rather referred to as "inborn errors of immunity" due to the association between a wide range of immune dysregulation-related clinical features and the "prototypic" increased infection susceptibility. The phenotypic spectrum of PIDs is therefore very large and includes several orofacial features. However, the latter are often overshadowed by severe systemic manifestations and remain underdiagnosed. Patients with impaired innate immunity are predisposed to a variety of oral manifestations including oral infections (e.g., candidiasis, herpes gingivostomatitis), aphthous ulcers, and severe periodontal diseases. Although less frequently, they can also show orofacial developmental abnormalities. Oral lesions can even represent the main clinical manifestation of some PIDs or be inaugural, being therefore one of the first features indicating the existence of an underlying immune defect. The aim of this review is to describe the orofacial features associated with the different PIDs of innate immunity based on the new 2019 classification from the International Union of Immunological Societies (IUIS) expert committee. This review highlights the important role played by the dentist, in close collaboration with the multidisciplinary medical team, in the management and the diagnostic of these conditions., (Copyright © 2020 Jung, Gies, Korganow and Guffroy.)

Background: The prognosis of patients with unresectable or metastatic biliary tract cancer (BTC) is unacceptably low. This study aimed to determine the efficacy, safety and predictive biomarkers of the immune checkpoint inhibitor nivolumab in combination with chemotherapy in advanced BTCs., Methods: In this open-label, single-arm, phase II trial, a chemotherapy and immunotherapy combination consisting of gemcitabine 1000 mg/m 2 , cisplatin 75 mg/m 2 and nivolumab 3 mg/kg was administered every 3 weeks for up to six cycles. Maintenance treatment with gemcitabine plus nivolumab was administered to patients achieving disease control following the combination therapy. The primary outcome was the objective response rate. Secondary outcomes included safety, disease control rate (DCR), progression-free survival (PFS) and overall survival (OS). The exploratory objective was to assess biomarkers for predicting clinical response and prognosis., Results: Thirty-two patients with a median age of 60 (range 27-69) years were enrolled. As of September 31, 2019, the median follow-up was 12.8 (95% CI 10.8 to 14.8) months. Twenty-seven response-evaluable patients received a median of 4 (IQR, 3-6) cycles of combination therapy, of whom 15 (55.6%) patients achieved an objective response, including 5 (18.6%) with a complete response (CR), and the DCR was 92.6%. Of the six patients in cohort A who were resistant to gemcitabine-based or cisplatin-based chemotherapy, one achieved CR and one achieved partial response. Thirteen of 21 chemotherapy-naive patients (61.9%) in cohort B achieved an objective response. The median PFS of all patients in cohorts A+B was 6.1 months. The median OS was 8.5 months, with a 33.3% 12-month OS rate. The most frequent grade 3 or higher adverse events were thrombocytopenia (56%) and neutropenia (22%). Fitness might be a biomarker for predicting clinical response. On-therapy changes in serum soluble FasL, MCP-1 and interferon-γ were correlated with prognosis., Conclusions: Nivolumab in combination with gemcitabine and cisplatin offers promising efficacy and a manageable safety profile for patients with advanced BTCs., Trial Registration Number: NCT03311789., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.)

Advances in genetics and sequencing have identified a plethora of disease-associated and disease-causing genetic alterations. To determine causality between genetics and disease, accurate models for molecular dissection are required; however, the rapid expansion of transcriptional populations identified through single-cell analyses presents a major challenge for accurate comparisons between mutant and wild-type cells. Here we generate mouse models of human severe congenital neutropenia (SCN) using patient-derived mutations in the GFI1 transcription factor. To determine the effects of SCN mutations, we generated single-cell references for granulopoietic genomic states with linked epitopes 1 , aligned mutant cells to their wild-type equivalents and identified differentially expressed genes and epigenetic loci. We find that GFI1-target genes are altered sequentially, as cells go through successive states of differentiation. These insights facilitated the genetic rescue of granulocytic specification but not post-commitment defects in innate immune effector function, and underscore the importance of evaluating the effects of mutations and therapy within each relevant cell state.

Neutrophils are the most abundant, yet with the shortest lifespan among the circulating leukocytes. These cells are produced in the bone marrow during granulopoiesis process. Severe congenital neutropenia (SCN) is a hematological disorder with disturbance in granulopoiesis process, in which the neutrophils apoptosis rate is escalated. Previous reports indicated that mesenchymal stem cells (MSCs), as an immunomodulator cell, could increase neutrophil lifespan in addition to the supportive effects on cardiomyocytes or the neuroprotective effects. In this study, MSCs were co-cultured with neutrophils isolated from SCN patients and healthy individuals. Then, we evaluated the MSC co-culture effects on neutrophils survival (annexin V/PI assay), reactive oxygen species (ROS) production (colorimetric NBT assay), and phagocytic activity (Giemsa staining after exposure to yeasts). It was demonstrated that MSC co-culture could increase neutrophil lifespan and phagocytic activity of the neutrophils isolated from SCN patients. Regarding healthy donors' neutrophils, only phagocytic activity improvement was seen. It could be concluded that MSCs could be considered as novel candidates for treatment of SCN patients., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Beyond their canonical roles in hemostasis and thrombosis, platelets function in the innate immune response by interacting directly with pathogens and by regulating the recruitment and activation of immune effector cells. Thrombocytopenia often coincides with neutropenia in patients with hematologic malignancies and in allogeneic hematopoietic cell transplant recipients, patient groups at high risk for invasive fungal infections. While neutropenia is well established as a major clinical risk factor for invasive fungal infections, the role of platelets in host defense against human fungal pathogens remains understudied. Here, we examined the role of platelets in murine Aspergillus fumigatus infection using two complementary approaches to induce thrombocytopenia without concurrent neutropenia. Thrombocytopenic mice were highly susceptible to A. fumigatus challenge and rapidly succumbed to infection. Although platelets regulated early conidial phagocytosis by neutrophils in a spleen tyrosine kinase (Syk)-dependent manner, platelet-regulated conidial phagocytosis was dispensable for host survival. Instead, our data indicated that platelets primarily function to maintain hemostasis and lung integrity in response to exposed fungal antigens, since thrombocytopenic mice exhibited severe hemorrhage into the airways in response to fungal challenge in the absence of overt angioinvasion. Challenge with swollen, heat-killed, conidia was lethal in thrombocytopenic hosts and could be reversed by platelet transfusion, consistent with the model that fungus-induced inflammation in platelet-depleted mice was sufficient to induce lethal hemorrhage. These data provide new insights into the role of platelets in the anti-Aspergillus host response and expand their role to host defense against filamentous molds., Competing Interests: The authors have declared that no competing interests exist.

Background: Chronic disseminated candidiasis (CDC) is a rare disease that mostly occurs after chemotherapy-induced prolonged neutropenia in patients with hematological malignancies. It is believed to ensue from Candida colonization, breach of the intestinal epithelial barrier, and venous translocation to organs. Fungal blood or liver biopsy cultures are generally negative, suggesting the absence of an ongoing invasive fungal disease., Methods: To unravel the contribution of the immune system to CDC pathogenesis, we undertook a prospective multicentric exploratory study in 44 CDC patients at diagnosis and 44 matched controls., Results: Analysis of Candida-specific T-cell responses using enzyme-linked immunospot assays revealed higher numbers of interferon (IFN)γ-producing T cells reactive to mp65 or candidin in 27 CDC cases compared with 33 controls. Increased plasma levels of soluble CD25, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and IL-10 and lower levels of IL-2 were observed in CDC patients versus controls. Neutrophilia and higher levels of CD4 and CD8 T-cell activation were found in CDC patients as well as increased proportions of CXCR3-expressing TCRγδ +Vδ2+ cells., Conclusions: The expansion of Candida-specific IFNγ-producing T cells together with features of T-cell activation and systemic inflammation identified here support the view that CDC belongs to the broad spectrum of fungal-associated immune reconstitution inflammatory syndromes., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Congenital cytomegalovirus (CCMV) accounts for high rates of infant morbidity and mortality. Neutropenia is a common finding in CCMV infection, of which the age of presentation overlaps with autoimmune neutropenia (AIN). AIN represents one of the most common forms of chronic neutropenia in childhood., Methods: A literature search exploring biologic associations between CCMV and AIN was conducted: PubMed (MEDLINE), Ovid and Web of Science. We further describe 2 cases of concurrent CCMV and AIN. Both cases were confirmed with the indirect granulocyte immunofluorescence test and alternative etiologies for neutropenia excluded., Results: Our 2 patients represent confirmed cases of AIN in infants with CCMV. One patient demonstrated neutropenia while undergoing treatment with Valganciclovir, while the other was never treated. With interruption of Valganciclovir in infant A, neutrophil counts (ANC) did not improve and upon resumption of treatment ANC remained static., Conclusions: Further studies examining a possible biologic link between CCMV and AIN are advocated for. We encourage clinicians to actively consider AIN in the differential diagnosis of all infants with CCMV presenting with neutropenia.

The existing data with regard to immune-related neutropenia (irN), a rare (incidence-1%) immune-related adverse event of immune checkpoint inhibitors, are scarce. Eight patients with irN were identified through internal databases of 3 participating Israeli cancer centers. In addition, 11 original articles focusing on the clinical course of 24 patients with irN were selected during the PubMed search. Descriptive analysis of clinical and pathologic factors related to irN was performed (n=32); the effect of these on the irN outcomes was assessed. An algorithm for irN evaluation and treatment was proposed. The median time-to-onset of irN (n=32) was 60 days (range, 10-465 d). Grade 3-5 irN, febrile neutropenia, and irN-related death occurred in 81%, 50%, and 9% of patients, respectively. In all, 56%, 22%, 62%, and 25% of patients received PO corticosteroids, IV corticosteroids, granulocyte colony-stimulating factor (GCSF), and intravenous immunoglobulins (IVIG), respectively, with an improvement/resolution rate of 84%. Odds ratios for irN improvement/resolution were as follows: 1.40 [95% confidence interval (CI), 0.03-68.72], 0.43 (95% CI, 0.04-4.22), 2.60 (95% CI, 0.07-97.24), 0.36 (95% CI, 0.03-4.38), 4.02 (95% CI, 0.16-99.48), 2.01 (95% CI, 0.32-12.70), 1.08 (95% CI, 0.02-49.89), 0.42 (95% CI, 0.06-2.91), and 2.73 (95% CI, 0.42-17.51) for granulocyte hyperplasia, granulocyte/all lineage hypoplasia, granulocyte maturation blockade, lymphocyte infiltration on bone marrow biopsy, IV corticosteroids, PO corticosteroids, cyclosporine, IVIG, and GCSF, respectively (P>0.05 for all factors). IrN recurrence rate following immune checkpoint inhibitors rechallenge was 80%. IrN is a rare, life-threatening, early-onset immune-related adverse event. Differentiating between the central, peripheral, and modified peripheral types allows a better prognosis definition. Corticosteroids and GCSF represent the main treatment approaches; IVIG and cyclosporine should be used as salvage treatment.

Neutropaenia is defined as an absolute neutrophil count (ANC) of less than 1500 cells/µL and is often divided into mild (ANC: 1000 to 1500 cells/µL), moderate (ANC: 500 to 1000 cells/µL) and severe (ANC: >500 cells/µL) neutropaenia. Autoimmune neutropaenia is arguably one of the most clinically relevant forms of neutropaenia and is defined by an ANC of <500 cells/µL alongside the confirmed presence of anti-neutrophil antibodies. It is a rare subset of neutropaenia boasting an incidence of just 1 in 100 000 infants and is thought to be caused as a result of a 'surveillance escape event' of the immune system. This case report identifies key issues in the diagnosis and monitoring of paediatric patients with recurrent neutropaenia and reviews current literature relating to its management in hospital and community settings., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)