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The neonatal fragment crystallizable (Fc) receptor (FcRn) functions as a recycling mechanism to prevent degradation and extend the half-life of IgG and albumin in the circulation. Several FcRn inhibitors selectively targeting IgG recycling are now moving rapidly toward clinical practice in neurology and hematology. These molecules accelerate the destruction of IgG, reducing pathogenic IgG and IgG immune complexes, with no anticipated effects on IgA, IgM, IgE, complement, plasma cells, B cells, or other cells of the innate or adaptive immune systems. FcRn inhibitors have potential for future use in a much wider variety of antibody-mediated autoimmune diseases. Given the imminent clinical use, potential for broader utility, and novel mechanism of action of FcRn inhibitors, here we review data from 4 main sources: (a) currently available activity, safety, and mechanism-of-action data from clinical trials of FcRn inhibitors; (b) other procedures and treatments that also remove IgG (plasma donation, plasma exchange, immunoadsorption); (c) diseases resulting in loss of IgG; and (d) primary immunodeficiencies with potential mechanistic similarities to those induced by FcRn inhibitors. These data have been evaluated to provide practical considerations for the assessment, monitoring, and reduction of any potential infection risk associated with FcRn inhibition, in addition to highlighting areas for future research., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Patients with X-linked hyper-IgM syndrome caused by CD40 ligand (CD40L) deficiency often present with episodic, cyclic, or chronic neutropenia, suggesting abnormal neutrophil development in the absence of CD40L-CD40 interaction. However, even when not neutropenic and despite immunoglobulin replacement therapy, CD40L-deficient patients are susceptible to life-threatening infections caused by opportunistic pathogens, suggesting impaired phagocyte function and the need for novel therapeutic approaches., Objectives: We sought to analyze whether peripheral neutrophils from CD40L-deficient patients display functional defects and to explore the in vitro effects of recombinant human IFN-γ (rhIFN-γ) on neutrophil function., Methods: We investigated the microbicidal activity, respiratory burst, and transcriptome profile of neutrophils from CD40L-deficient patients. In addition, we evaluated whether the lack of CD40L in mice also affects neutrophil function., Results: Neutrophils from CD40L-deficient patients exhibited defective respiratory burst and microbicidal activity, which were improved in vitro by rhIFN-γ but not soluble CD40L. Moreover, neutrophils from patients showed reduced CD16 protein expression and a dysregulated transcriptome suggestive of impaired differentiation. Similar to CD40L-deficient patients, CD40L knockout mice were found to have impaired neutrophil responses. In parallel, we demonstrated that soluble CD40L induces the promyelocytic cell line HL-60 to proliferate and mature by regulating the expression of genes of the same Gene Ontology categories (eg, cell differentiation) when compared with those dysregulated in peripheral blood neutrophils from CD40L-deficient patients., Conclusion: Our data suggest a nonredundant role of CD40L-CD40 interaction in neutrophil development and function that could be improved in vitro by rhIFN-γ, indicating a potential novel therapeutic application for this cytokine., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia (XLT), and X-linked neutropenia, which are caused by WAS mutations affecting Wiskott-Aldrich syndrome protein (WASp) expression or activity, manifest in immunodeficiency, autoimmunity, genomic instability, and lymphoid and other cancers. WASp supports filamentous actin formation in the cytoplasm and gene transcription in the nucleus. Although the genetic basis for XLT/WAS has been clarified, the relationships between mutant forms of WASp and the diverse features of these disorders remain ill-defined., Objective: We sought to define how dysfunctional gene transcription is causally linked to the degree of T H cell deficiency and genomic instability in the XLT/WAS clinical spectrum., Methods: In human T H 1- or T H 2-skewing cell culture systems, cotranscriptional R-loops (RNA/DNA duplex and displaced single-stranded DNA) and DNA double-strand breaks (DSBs) were monitored in multiple samples from patients with XLT and WAS and in normal T cells depleted of WASp., Results: WASp deficiency provokes increased R-loops and R-loop-mediated DSBs in T H 1 cells relative to T H 2 cells. Mechanistically, chromatin occupancy of serine 2-unphosphorylated RNA polymerase II is increased, and that of topoisomerase 1, an R-loop preventing factor, is decreased at R-loop-enriched regions of IFNG and TBX21 (T H 1 genes) in T H 1 cells. These aberrations accompany increased unspliced (intron-retained) and decreased spliced mRNA of IFNG and TBX21 but not IL13 (T H 2 gene). Significantly, increased cellular load of R-loops and DSBs, which are normalized on RNaseH1-mediated suppression of ectopic R-loops, inversely correlates with disease severity scores., Conclusion: Transcriptional R-loop imbalance is a novel molecular defect causative in T H 1 immunodeficiency and genomic instability in patients with WAS. The study proposes that cellular R-loop load could be used as a potential biomarker for monitoring symptom severity and prognostic outcome in the XLT-WAS clinical spectrum and could be targeted therapeutically., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Background: We evaluated the overall and site-specific incidence of cancer in subjects with primary immunodeficiency diseases (PIDD) enrolled in the United States Immune Deficiency Network (USIDNET) registry compared with age-adjusted cancer incidence in the Surveillance, Epidemiology and End Results Program (SEER) database., Objective: We hypothesized that subjects with PIDD would have an increased incidence of cancer due to impaired immune function., Methods: Overall and site-specific cancer incidence rates were evaluated in subjects with PIDD (n = 3658) enrolled in the USIDNET registry from 2003 to 2015 and compared with age-adjusted incidence rates in the SEER database., Results: We observed a 1.42-fold excess relative risk of cancer in subjects with PIDD compared with the age-adjusted SEER population (P < .001). Men with PIDD had a 1.91-fold excess relative risk of cancer compared with the age-adjusted male population (P < .001), while women with PIDD had similar overall cancer rates compared with the age-adjusted female population. Of the 4 most common malignancies in men and women in SEER (lung, colon, breast, and prostate cancers), we found no significant increase in these diagnoses in subjects with PIDD. Significant increases in lymphoma in both men (10-fold increase, P < .001) and women (8.34-fold increase, P < .001) with PIDD were observed., Conclusions: Excess incidence of cancer occurred in subjects with PIDD. An excess of lymphoma in specific PIDD populations principally drove this increased incidence, while no increased risk of the most common solid tumor malignancies was observed. These data point to a restricted role of the immune system in protecting from specific cancers., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. All rights reserved.)

Background: Gain-of-function (GOF) mutations in signal transducer and activator of transcription 1 (STAT1) cause susceptibility to a range of infections, autoimmunity, immune dysregulation, and combined immunodeficiency. Disease manifestations can be mild or severe and life-threatening. Hematopoietic stem cell transplantation (HSCT) has been used in some patients with more severe symptoms to treat and cure the disorder. However, the outcome of HSCT for this disorder is not well established., Objective: We sought to aggregate the worldwide experience of HSCT in patients with GOF-STAT1 mutations and to assess outcomes, including donor engraftment, overall survival, graft-versus-host disease, and transplant-related complications., Methods: Data were collected from an international cohort of 15 patients with GOF-STAT1 mutations who had undergone HSCT using a variety of conditioning regimens and donor sources. Retrospective data collection allowed the outcome of transplantation to be assessed. In vitro functional testing was performed to confirm that each of the identified STAT1 variants was in fact a GOF mutation., Results: Primary donor engraftment in this cohort of 15 patients with GOF-STAT1 mutations was 74%, and overall survival was only 40%. Secondary graft failure was common (50%), and posttransplantation event-free survival was poor (10% by 100 days). A subset of patients had hemophagocytic lymphohistiocytosis before transplant, contributing to their poor outcomes., Conclusion: Our data indicate that HSCT for patients with GOF-STAT1 mutations is curative but has significant risk of secondary graft failure and death., (Copyright © 2017. Published by Elsevier Inc.)

Background: X-linked hyper-IgM syndrome (XHIGM) is a primary immunodeficiency with high morbidity and mortality compared with those seen in healthy subjects. Hematopoietic cell transplantation (HCT) has been considered a curative therapy, but the procedure has inherent complications and might not be available for all patients., Objectives: We sought to collect data on the clinical presentation, treatment, and follow-up of a large sample of patients with XHIGM to (1) compare long-term overall survival and general well-being of patients treated with or without HCT along with clinical factors associated with mortality and (2) summarize clinical practice and risk factors in the subgroup of patients treated with HCT., Methods: Physicians caring for patients with primary immunodeficiency diseases were identified through the Jeffrey Modell Foundation, United States Immunodeficiency Network, Latin American Society for Immunodeficiency, and Primary Immune Deficiency Treatment Consortium. Data were collected with a Research Electronic Data Capture Web application. Survival from time of diagnosis or transplantation was estimated by using the Kaplan-Meier method compared with log-rank tests and modeled by using proportional hazards regression., Results: Twenty-eight clinical sites provided data on 189 patients given a diagnosis of XHIGM between 1964 and 2013; 176 had valid follow-up and vital status information. Sixty-seven (38%) patients received HCT. The average follow-up time was 8.5 ± 7.2 years (range, 0.1-36.2 years). No difference in overall survival was observed between patients treated with or without HCT (P = .671). However, risk associated with HCT decreased for diagnosis years 1987-1995; the hazard ratio was significantly less than 1 for diagnosis years 1995-1999. Liver disease was a significant predictor of overall survival (hazard ratio, 4.9; 95% confidence limits, 2.2-10.8; P < .001). Among survivors, those treated with HCT had higher median Karnofsky/Lansky scores than those treated without HCT (P < .001). Among patients receiving HCT, 27 (40%) had graft-versus-host disease, and most deaths occurred within 1 year of transplantation., Conclusion: No difference in survival was observed between patients treated with or without HCT across all diagnosis years (1964-2013). However, survivors treated with HCT experienced somewhat greater well-being, and hazards associated with HCT decreased, reaching levels of significantly less risk in the late 1990s. Among patients treated with HCT, treatment at an early age is associated with improved survival. Optimism remains guarded as additional evidence accumulates., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: CD40 ligand (CD40L) deficiency predisposes to opportunistic infections, including those caused by fungi and intracellular bacteria. Studies of CD40L-deficient patients reveal the critical role of CD40L-CD40 interaction for the function of T, B, and dendritic cells. However, the consequences of CD40L deficiency on macrophage function remain to be investigated., Objectives: We sought to determine the effect of CD40L absence on monocyte-derived macrophage responses., Methods: After observing the improvement of refractory disseminated mycobacterial infection in a CD40L-deficient patient by recombinant human IFN-γ (rhIFN-γ) adjuvant therapy, we investigated macrophage functions from CD40L-deficient patients. We analyzed the killing activity, oxidative burst, cytokine production, and in vitro effects of rhIFN-γ and soluble CD40 ligand (sCD40L) treatment on macrophages. In addition, the effect of CD40L absence on the macrophage transcriptome before and after rhIFN-γ treatment was studied., Results: Macrophages from CD40L-deficient patients exhibited defective fungicidal activity and reduced oxidative burst, both of which improved in the presence of rhIFN-γ but not sCD40L. In contrast, rhIFN-γ and sCD40L ameliorate impaired production of inflammatory cytokines. Furthermore, rhIFN-γ reversed defective control of Mycobacterium tuberculosis proliferation by patients' macrophages. The absence of CD40L dysregulated the macrophage transcriptome, which was improved by rhIFN-γ. Additionally, rhIFN-γ increased expression levels of pattern recognition receptors, such as Toll-like receptors 1 and 2, dectin 1, and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin in macrophages from both control subjects and patients., Conclusion: Absence of CD40L impairs macrophage development and function. In addition, the improvement of macrophage immune responses by IFN-γ suggests this cytokine as a potential therapeutic option for patients with CD40L deficiency., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: The molecular mechanism of class-switch recombination (CSR) in human subjects has not been fully elucidated. The CSR-induced mutations occurring in the switch region of the IgM gene (Smu-SHMs) in in vitro CSR-activated and in vivo switched B cells have been analyzed in mice but not in human subjects., Objective: We sought to better characterize the molecular mechanism of CSR in human subjects., Methods: Smu-SHMs were analyzed in vitro and in vivo by using healthy control subjects and patients with molecularly defined CSR defects., Results: We found that Smu-SHMs can be induced in vitro by means of CSR activation in human subjects. We also found large amounts of Smu-SHMs in in vivo class-switched memory B cells, smaller (although significant) amounts in unswitched memory B cells, and very low amounts in naive B cells. In class-switched memory B cells a high frequency of Smu-SHMs was found throughout the Smu. In unswitched memory B cells, the Smu-SHM frequency was significantly decreased in the 5' part of the Smu. The difference between switched and unswitched B cells suggests that the extension of somatic hypermutation (SHM) to the 5' upstream region of the Smu might be associated with the effective induction of CSR. The analysis of the pattern of mutations within and outside the WRCY/RGYW (W, A/T; R, A/G; and Y, C/T) motifs, as well as the Smu-SHMs, in CD27(+) B cells from CD40 ligand (CD40L)-, activation-induced cytidine deaminase (AID)-, and uracil-DNA glycosylase (UNG)-deficient patients revealed the dependence of Smu-SHM on CD40L, AID, UNG, and the mismatch repair system in human subjects., Conclusion: CD40L-, AID-, UNG-, and mismatch repair system-dependent Smu-SHMs and extension to the 5' region of Smu are necessary to accomplish effective CSR in human subjects., (Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

The present uncertainty of which live viral or bacterial vaccines can be given to immunodeficient patients and the growing neglect of societal adherence to routine immunizations has prompted the Medical Advisory Committee of the Immune Deficiency Foundation to issue recommendations based on published literature and the collective experience of the committee members. These recommendations address the concern for immunodeficient patients acquiring infections from healthy subjects who have not been immunized or who are shedding live vaccine-derived viral or bacterial organisms. Such transmission of infectious agents can occur within the hospital, clinic, or home or at any public gathering. Collectively, we define this type of transmission as close-contact spread of infectious disease that is particularly relevant in patients with impaired immunity who might have an infection when exposed to subjects carrying vaccine-preventable infectious diseases or who have recently received a live vaccine. Immunodeficient patients who have received therapeutic hematopoietic stem transplantation are also at risk during the time when immune reconstitution is incomplete or while they are receiving immunosuppressive agents to prevent or treat graft-versus-host disease. This review recommends the general education of what is known about vaccine-preventable or vaccine-derived diseases being spread to immunodeficient patients at risk for close-contact spread of infection and describes the relative risks for a child with severe immunodeficiency. The review also recommends a balance between the need to protect vulnerable subjects and their social needs to integrate into society, attend school, and benefit from peer education., (Published by Mosby, Inc.)

The Primary Immune Deficiency Treatment Consortium (PIDTC) is a network of 33 centers in North America that study the treatment of rare and severe primary immunodeficiency diseases. Current protocols address the natural history of patients treated for severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome, and chronic granulomatous disease through retrospective, prospective, and cross-sectional studies. The PIDTC additionally seeks to encourage training of junior investigators, establish partnerships with European and other International colleagues, work with patient advocacy groups to promote community awareness, and conduct pilot demonstration projects. Future goals include the conduct of prospective treatment studies to determine optimal therapies for primary immunodeficiency diseases. To date, the PIDTC has funded 2 pilot projects: newborn screening for SCID in Navajo Native Americans and B-cell reconstitution in patients with SCID after hematopoietic stem cell transplantation. Ten junior investigators have received grant awards. The PIDTC Annual Scientific Workshop has brought together consortium members, outside speakers, patient advocacy groups, and young investigators and trainees to report progress of the protocols and discuss common interests and goals, including new scientific developments and future directions of clinical research. Here we report the progress of the PIDTC to date, highlights of the first 2 PIDTC workshops, and consideration of future consortium objectives., (Published by Mosby, Inc.)

This Current perspectives article will review and highlight the importance of accurate diagnosis of patients who have failed to produce specific antibodies to naturally encountered foreign proteins or polysaccharides or after vaccination and the appropriate institution of immunoglobulin replacement therapy. The field of primary immunodeficiency disease (PIDD) has expanded remarkably since the early descriptions 6 decades ago. With greater recognition and advanced cellular and molecular diagnostic technology, new entities and single-gene defects in patients with PIDD are rapidly being defined. This, combined with treatment advances and newborn screening for severe combined immunodeficiency, has resulted in improved outcomes and survival and even permanent cures. Awareness of PIDD has also increased, but the guidelines for recognition remain to be validated. The zeal for registering and enrolling patients has potentially created a large body of "patients" treated with immunoglobulin replacement unnecessarily. The complexity, diversity, and availability of laboratory testing have brought awareness of PIDD to the forefront, but because of an absence of standardization of certain assays, concerns about the correct diagnosis and appropriate treatment have increased. We hope to refocus the discussion on identifying clear laboratory and clinical guidelines for the establishment of an accurate diagnosis of antibody deficiency, its rationale, and, where indicated, institution of safe treatment., (Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Patients with X-linked hyper-IgM syndrome (X-HIGM) due to CD40 ligand (CD40L) mutations are susceptible to fungal pathogens; however, the underlying susceptibility mechanisms remain poorly understood., Objective: To determine whether monocyte-derived dendritic cells (DCs) from patients with X-HIGM exhibit normal responses to fungal pathogens., Methods: DCs from patients and controls were evaluated for the expression of costimulatory (CD80 and CD86) and MHC class II molecules and for their ability to produce IL-12 and IL-10 in response to Candida albicans and Paracoccidioides brasiliensis. We also evaluated the ability of C albicans- and P brasiliensis-pulsed mature DCs to induce autologous T-cell proliferation, generation of T helper (T(H)) 17 cells, and production of IFN-γ, TGF-β, IL-4, IL-5, and IL-17., Results: Immature DCs from patients with X-HIGM showed reduced expression of CD80, CD86, and HLA-DR, which could be reversed by exogenous trimeric soluble CD40L. Most important, mature DCs from patients with X-HIGM differentiated by coculturing DCs with fungi secreted minimal amounts of IL-12 but substantial amounts of IL-10 compared with mature DCs from normal individuals. Coculture of mature DCs from X-HIGM patients with autologous T cells led to low IFN-γ production, whereas IL-4 and IL-5 production was increased. T-cell proliferation and IL-17 secretion were normal. Finally, in vitro incubation with soluble CD40L reversed the decreased IL-12 production and the skewed T(H)2 pattern response., Conclusion: Absence of CD40L during monocyte/DC differentiation leads to functional DC abnormalities, which may contribute to the susceptibility to fungal infections in patients with X-HIGM., (Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: B-lymphocyte depletion with rituximab has been shown to benefit patients with various autoimmune diseases. We have previously demonstrated that this benefit is also apparent in patients with newly diagnosed type 1 diabetes., Objectives: The effect of rituximab on in vivo antibody responses, particularly during the period of B-lymphocyte depletion, is incompletely determined. This study was designed to assess this knowledge void., Methods: In patients with recent-onset type 1 diabetes treated with rituximab (n = 46) or placebo (n = 29), antibody responses to neoantigen phiX174 during B-lymphocyte depletion and with hepatitis A (as a second neoantigen) and tetanus/diphtheria (as recall antigens) after B-lymphocyte recovery were studied. Anti- tetanus, diphtheria, mumps, measles, and rubella titers were measured before and after treatment by means of ELISA. Antibody titers and percentage IgM versus percentage IgG to phiX174 were measured by means of phage neutralization. B-lymphocyte subsets were determined by means of flow cytometry., Results: No change occurred in preexisting antibody titers. Tetanus/diphtheria and hepatitis A immunization responses were protective in the rituximab-treated subjects, although significantly blunted compared with those seen in the controls subjects, when immunized at the time of B-lymphocyte recovery. Anti-phiX174 responses were severely reduced during the period of B-lymphocyte depletion, but with B-lymphocyte recovery, anti-phiX174 responses were within the normal range., Conclusions: During the time of B-lymphocyte depletion, rituximab recipients had a decreased antibody response to neoantigens and significantly lower titers after recall immunization with diphtheria and tetanus toxoid. With recovery, immune responses return toward normal. Immunization during the time of B-lymphocyte depletion, although ineffective, does not preclude a subsequent response to the antigen., (Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Cartilage-hair hypoplasia (CHH) is characterized by metaphyseal dysplasia, bone marrow failure, increased risk of malignancies, and a variable degree of immunodeficiency. CHH is caused by mutations in the RNA component of the mitochondrial RNA processing (RMRP) endoribonuclease gene, which is involved in ribosomal assembly, telomere function, and cell cycle control., Objectives: We aimed to define thymic output and characterize immune function in a cohort of patients with molecularly defined CHH with and without associated clinical immunodeficiency., Methods: We studied the distribution of B and T lymphocytes (including recent thymic emigrants), in vitro lymphocyte proliferation, cell cycle, and apoptosis in 18 patients with CHH compared with controls., Results: Patients with CHH have a markedly reduced number of recent thymic emigrants, and their peripheral T cells show defects in cell cycle control and display increased apoptosis, resulting in poor proliferation on activation., Conclusion: These data confirm that RMRP mutations result in significant defects of cell-mediated immunity and provide a link between the cellular phenotype and the immunodeficiency in CHH., (Copyright © 2011 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is characterized by severe systemic autoimmunity caused by mutations in the forkhead box protein 3 (FOXP3) gene. Hematopoietic cell transplantation is currently the only viable option for long-term survival, but patients are frequently very ill and may not tolerate traditional myeloablative conditioning regimens., Objective: Here we present the outcome of hematopoietic cell transplantation using a low-intensity, nonmyeloablative conditioning regimen in 2 patients with IPEX syndrome and significant pretransplant risk factors., Methods: Two high-risk patients with IPEX syndrome received HLA-matched related bone marrow or unrelated peripheral blood stem cell grafts following conditioning with 90 mg/m(2) fludarabine and 4 Gy total body irradiation. Postgrafting immunosuppression consisted of mycophenolate mofetil and cyclosporine. Immune reconstitution and immune function was evaluated by measurement of donor chimerism, regulatory T-cell numbers, absolute lymphocyte subsets, and T-cell proliferation assays., Results: Both patients experienced minimal conditioning toxicity and successfully engrafted after hematopoietic cell transplantation. With a follow-up of 4 and 1 years, respectively, patients 1 and 2 have full immune function and normal FOXP3 protein expression., Conclusion: A low-intensity, nonmyeloablative conditioning regimen can establish stable engraftment and correct the life-threatening immune deficiency and enteropathy of IPEX syndrome despite the presence of comorbidities that preclude conventional hematopoietic cell transplantation., (Copyright © 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Background: Hyper-IgE syndromes (HIES) are primary immunodeficiency disorders characterized by Staphylococcus aureus abscesses, recurrent pneumonia, increased serum IgE levels, and eczema. The association of heterozygous signal transducer and activator of transcription 3 (STAT3) mutations with autosomal dominant (AD)-HIES allows the differentiation of AD-HIES from disorders associated with eczema and increased serum IgE levels, such as other primary immunodeficiencies and atopic dermatitis., Objective: To facilitate early diagnosis of AD-HIES to initiate appropriate therapy., Methods: The clinical phenotype (suggested by a National Institutes of Health [NIH] score of >or=40 points), STAT3 genotype, and T(H)17 cell counts were compared in a cohort of 78 patients suspected of having HIES., Results: Heterozygous STAT3 missense mutations and in-frame deletions were identified in 48 patients, all but 2 with an NIH score >or=40 points. Patients with STAT3 mutations with HIES showed significantly lower T(H)17 cell counts compared with patients with wild-type STAT3 and control subjects. Only 1 patient with wild-type STAT3 had both an NIH score >or=40 points and abnormal T(H)17 cell counts (

More than 50 years after Ogdeon Bruton's discovery of congenital agammaglobulinemia, human primary immunodeficiencies (PIDs) continue to unravel novel molecular and cellular mechanisms that govern development and function of the human immune system. This report provides the updated classification of PIDs that has been compiled by the International Union of Immunological Societies Expert Committee on Primary Immunodeficiencies after its biannual meeting in Dublin, Ireland, in June 2009. Since the appearance of the last classification in 2007, novel forms of PID have been discovered, and additional pathophysiology mechanisms that account for PID in human beings have been unraveled. Careful analysis and prompt recognition of these disorders is essential to prompt effective forms of treatment and thus to improve survival and quality of life in patients affected with PIDs.

More than 20 North American academic centers account for the majority of hematopoietic stem cell transplantation (HCT) procedures for primary immunodeficiency diseases (PIDs), with smaller numbers performed at additional sites. Given the importance of a timely diagnosis of these rare diseases and the diversity of practice sites, there is a need for guidance as to best practices in management of patients with PIDs before, during, and in follow-up for definitive treatment. In this conference report of immune deficiency experts and HCT physicians who care for patients with PIDs, we present expert guidance for (1) PID diagnoses that are indications for HCT, including severe combined immunodeficiency disease (SCID), combined immunodeficiency disease, and other non-SCID diseases; (2) the critical importance of a high degree of suspicion of the primary care physician and timeliness of diagnosis for PIDs; (3) the need for rapid referral to an immune deficiency expert, center with experience in HCT, or both for patients with PIDs; (4) medical management of a child with suspicion of SCID/combined immunodeficiency disease while confirming the diagnosis, including infectious disease management and workup; (5) the posttransplantation follow-up visit schedule; (6) antimicrobial prophylaxis after transplantation, including gamma globulin administration; and (7) important indications for return to the transplantation center after discharge. Finally, we discuss the role of high-quality databases in treatment of PIDs and HCT as an element of the infrastructure that will be needed for productive multicenter clinical trials in these rare diseases.

Background: Mutations in serine protease inhibitor Kazal-type 5 (SPINK5), encoding the serine protease inhibitor lympho-epithelial Kazal-type 5 related inhibitor (LEKTI), cause Comèl-Netherton syndrome, an autosomal-recessive disease characterized by congenital ichthyosis, bamboo hair, and atopic diathesis. Despite increased frequency of infections, the immunocompetence of patients with Comèl-Netherton syndrome has not been extensively investigated., Objective: To define Comèl-Netherton syndrome as a primary immunodeficiency disorder and to explore the benefit of intravenous immunoglobulin replacement therapy., Methods: We enrolled 9 patients with Comèl-Netherton syndrome, sequenced SPINK5, and analyzed LEKTI expression by immunohistochemistry. Immune function was assessed by measuring cognate immunity, serum cytokine levels, and natural killer cell cytotoxicity., Results: All patients presented with recurrent skin infections caused predominantly by Staphylococcus aureus. All but 1 reported recurrent respiratory tract infections; 78% had sepsis and/or pneumonia; 67% had recurrent gastrointestinal disease and failure to thrive. Mutations in SPINK5-including 6 novel mutations-were identified in 8 patients. LEKTI expression was decreased or absent in all patients. Immunologic evaluation revealed reduced memory B cells and defective responses to vaccination with Pneumovax and bacteriophage phiX174, characterized by impaired antibody amplification and class-switching. Immune dysregulation was suggested by a skewed T(h)1 phenotype and elevated proinflammatory cytokine levels, whereas serum concentrations of the chemokine (C-C motif) ligand 5 and natural killer cell cytotoxicity were decreased. Treatment with intravenous immunoglobulin resulted in remarkable clinical improvement and temporarily increased natural killer cell cytotoxicity., Conclusion: These data provide new insights into the immunopathology of Comèl-Netherton syndrome and demonstrate that this multisystem disorder, characterized by lack of LEKTI expression in epithelial cells, is complicated by cognate and innate immunodeficiency that responds favorably to intravenous immunoglobulin therapy.

After activation by unique cytokines, CD4(+) naive T cells differentiate into lineages of helper/effector (T(H)) and regulatory T (Treg) cells that are characterized by distinct developmental pathways and unique biologic functions. The trusted binary system of T(H)1 and T(H)2 has been expanded to include the IL-17-producing T(H)17 cell lineage, which plays a role in immune responses to infectious agents and maintenance of autoimmune diseases. Acting as counterbalance, Treg cells maintain peripheral tolerance and protect the host from autoaggressive lymphocytes. T(H)1 cells produce IFN-gamma and are involved in cell-mediated immunity, T(H)2 cells produce IL-4 and contribute to humoral immunity, T(H)17 cells generate IL-17 and play an important role in immune responses to fungi and extracellular pathogens, and forkhead box protein 3-positive (FOXP3(+)) Treg cells secrete TGF-beta and IL-10 and downregulate effector T cells. Autosomal dominant hyper-IgE syndrome, a rare primary immunodeficiency disorder, is caused by hypomorphic heterozygous mutations of signal transducer and activator of transcription 3 (STAT3), preventing T(H)17 lineage differentiation and increasing susceptibility to Staphylococcus and Candida species infections. Mutations in the FOXP3 gene interfere with Treg cell development and cause immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome. Other single-gene defects resulting in reduced Treg cell function include CD25, signal transducer and activator of transcription 5b, autoimmune regulator, and Wiskott-Aldrich syndrome protein. These observations emphasize the importance of functionally distinct T-cell lineages in maintaining a balanced innate and cognate immune system.

Background: It is unknown whether a prolonged period of bed rest will affect human immune responses, particularly in female subjects., Objective: We sought to measure immune responses in adult female subjects exposed to prolonged bed rest., Methods: Adult (25-40 years) female volunteers (n = 24) were maintained in a supine (6 degrees tilt) head-down bed-rest (HDBR) position for 60 days: 8 with HDBR only, 8 with HDBR and regular muscular exercise, and 8 with HDBR and dietary protein supplementation. Subjects were immunized with bacteriophage phiX-174. Antibody production and plasma cytokine levels were determined., Results: The rate of primary antibody production of the HDBR plus exercise group increased faster (P = .01) and to a higher level versus that of the HDBR-only group (P = .03) and that of the HDBR plus diet group (trend P = .08). The rates of secondary antibody production between the 3 groups were similar, but the level of antibody in the HDBR plus exercise group remained higher versus that in the HDBR-only group (P = .03). Both the HDBR (P = .001) and HDBR plus diet (P = .02) groups had time-related progressive increases in TNF-alpha receptor levels, but the HDBR plus exercise group remained at baseline. The HDBR plus exercise group experienced an acute increase in IL-1 receptor antagonist levels versus the HDBR (P = .02) and the HDBR plus diet (P = .02) groups, with similar increases in RANTES levels., Conclusions: The exercise countermeasure accelerated primary antibody production and increased antibody levels to bacteriophage phiX-174 and also opposed the potentially harmful effects of increased TNF-alpha levels caused by prolonged bed rest, possibly by activating the anti-inflammatory cytokine IL-1 receptor antagonist and the chemotactic factor RANTES.

Background: Hyper-IgE syndrome (HIES) is a rare, autosomal-dominant immunodeficiency characterized by eczema, Staphylococcus aureus skin abscesses, pneumonia with pneumatocele formation, Candida infections, and skeletal/connective tissue abnormalities. Recently it was shown that heterozygous signal transducer and activator of transcription 3 (STAT3) mutations cause autosomal-dominant HIES., Objective: To determine the spectrum and functional consequences of heterozygous STAT3 mutations in a cohort of patients with HIES., Methods: We sequenced the STAT3 gene in 38 patients with HIES (National Institutes of Health score >40 points) from 35 families, quantified T(H)17 cells in peripheral blood, and evaluated tyrosine phosphorylation of STAT3., Results: Most STAT3 mutations in our cohort were in the DNA-binding domain (DBD; 22/35 families) or Src homology 2 (SH2) domain (10/35) and were missense mutations. We identified 2 intronic mutations resulting in exon skipping and in-frame deletions within the DBD. In addition, we identified 2 mutations located in the transactivation domain downstream of the SH2 domain: a 10-amino acid deletion and an amino acid substitution. In 1 patient, we were unable to identify a STAT3 mutation. T(H)17 cells were absent or low in the peripheral blood of all patients who were evaluated (n = 17). IL-6-induced STAT3-phosphorylation was consistently reduced in patients with SH2 domain mutations but comparable to normal controls in patients with mutations in the DBD., Conclusion: Heterozygous STAT3 mutations were identified in 34 of 35 unrelated HIES families. Patients had impaired T(H)17 cell development, and those with SH2 domain mutations had reduced STAT3 phosphorylation.

Primary immunodeficiency diseases (PIDs) are a genetically heterogeneous group of disorders that affect distinct components of the innate and adaptive immune system, such as neutrophils, macrophages, dendritic cells, complement proteins, natural killer cells, and T and B lymphocytes. The study of these diseases has provided essential insights into the functioning of the immune system. More than 120 distinct genes have been identified, whose abnormalities account for more than 150 different forms of PID. The complexity of the genetic,immunologic, and clinical features of PID has prompted the need for their classification, with the ultimate goal of facilitating diagnosis and treatment. To serve this goal, an international committee of experts has met every 2 years since 1970. In its last meeting in Jackson Hole, Wyo, after 3 days of intense scientific presentations and discussions, the committee has updated the classification of PID, as reported in this article.

The rare X-linked disorder immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) and its murine counterpart scurfy have provided important new insights into the essential role of regulatory T cells (Treg) in maintaining tolerance to self-antigens. Mutations of the FOXP3 gene, identified in patients with IPEX, have helped pinpoint key structural domains of the protein that are essential for its function as a transcriptional regulator. Ongoing work using these and associated models has begun to elucidate factors important for the development, function, and competitive fitness of Treg. This improved understanding is beginning to lead to the identification of other defects that may be present in patients who have the clinical phenotype of IPEX but only wild-type FOXP3. It has also led to improved treatment options for IPEX including immunosuppressive drugs and bone marrow transplantation. We are hopeful that the knowledge gained about mechanisms that regulate FOXP3 expression and Treg function will have a major effect on how other autoimmune and allergic disorders are approached.

The Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder with variable clinical phenotypes that correlate with the type of mutations in the WAS protein (WASP) gene. WASP, a key regulator of actin polymerization in hematopoietic cells, has 5 well-defined domains that are involved in signaling, cell locomotion, and immune synapse formation. WASP facilitates the nuclear translocation of nuclear factor kappaB and was shown to play an important role in lymphoid development and in the maturation and function of myeloid monocytic cells. Mutations of WASP are located throughout the gene and either inhibit or dysregulate normal WASP function. Analysis of a large patient population demonstrates a phenotype-genotype correlation: classic WAS occurs when WASP is absent, X-linked thrombocytopenia when mutated WASP is expressed, and X-linked neutropenia when missense mutations occur in the Cdc42-binding site. The progress made in dissecting the function of WASP has provided new diagnostic possibilities and has propelled our therapeutic strategies from conservative symptomatic treatment to curative hematopoietic stem cell transplantation and toward gene therapy.

IPEX (immune-dysregulation, polyendocrinopathy, enteropathy, X-linked) syndrome is an autoimmune disorder with an often lethal outcome in spite of immunosuppressive therapy. We report the successful use of sirolimus in 3 patients with IPEX. The efficacy of sirolimus is probably due to its different mode of action compared to calcineurin-dependent agents.

Background: Inducible CO-stimulatory molecule (ICOS), the third member of the CD28/CTLA4 family, is expressed by activated T cells and interacts with its ligand (ICOSL, B7-related protein-1 [B7RP-1]) that is constitutively expressed by B cells. The interaction of ICOS with its ligand leads to terminal differentiation of B cells to plasma cells. ICOS-deficient mice fail to undergo immunoglobulin-class switch recombination (CSR) and germinal center formation, suggesting that ICOS could be a candidate gene for phenotypic hyper-IgM (HIGM) syndromes characterized by recurrent infections, low serum IgG and IgA, and normal or elevated IgM. Genetically, at least 4 distinct molecular defects have been identified that result in defective CSR and present as HIGM syndromes: defects of the CD40 ligand gene (CD40L; HIGM1, X-linked), the activation-induced cytidine deaminase gene (AID; HIGM2, autosomal recessive), the CD40 gene (HIGM3, autosomal recessive), and the nuclear factor-kappaB (NF-kappaB) essential modulator gene (NEMO, or IKK-gamma, X-linked). In a substantial subgroup of HIGM patients, these 4 genes are normal, and the genetic defect is unknown., Objective: We sought to investigate the possibility that mutations of ICOS could account for some patients' belonging to this HIGM subgroup., Methods: The expression of ICOS protein by activated peripheral blood mononuclear cells and/or interleukin-2-dependent T cell lines derived from these patients was estimated by flow cytometery after incubation of the cells with the ICOS ligand fusion protein B7RP-1 Fc. The coding region and exon-intron boundaries of ICOS were assessed by sequence analysis., Results: We studied 33 HIGM patients from 30 families, selected from an original cohort of 136 patients from 113 families, by excluding mutations of CD40L, AID, CD40, and NEMO. Activated T cells from all 33 patients expressed ICOS normally, and sequence analysis of the coding region and exon-intron boundaries revealed only wild-type ICOS, predicting that the protein structure is normal in this patient population., Conclusion: These findings strongly suggest that ICOS does not belong to the group of genes that, if mutated, present clinically as the HIGM syndrome.

Background: Alefacept, human LFA-3/IgG(1) fusion protein, selectively reduces memory-effector (CD45RO(+)) T cells, a source of the pathogenic mediators of psoriasis., Objective: To evaluate the effect of alefacept on immune function, T-cell-dependent humoral responses to a neoantigen (PhiX174) and recall antigen (tetanus toxoid) were assessed., Methods: Patients with psoriasis were randomized to the control group or to receive alefacept (7.5 mg intravenously weekly for 12 weeks). The alefacept group received PhiX174 immunizations at weeks 6, 12, 20, and 26 and tetanus toxoid at week 21; control subjects received PhiX174 at weeks 6 and 12 and tetanus at week 10., Results: Mean anti-PhiX174 titers were comparable in both groups. There was no difference in the percentage of responders (anti-PhiX174 IgG >/=30% of the total anti-PhiX174) between the alefacept group and the control group (86% and 82%, respectively; P =.73). The percentage of patients with anti-tetanus toxoid titer increases >/=2 times baseline also was similar (alefacept, 89%; control 91%)., Conclusion: A single 12-week course of alefacept did not impair primary or secondary antibody responses to a neoantigen or memory responses to a recall antigen. The selective immunomodulatory effect of alefacept against a potentially pathogenic T-cell subset is associated with maintenance of a significant aspect of immune function (antibody response) to fight infection and respond to vaccinations.

Banked unrelated umbilical cord blood matched at 5 of 6 human leukocyte antigen loci was used to reconstitute the immune system in 2 brothers with X-linked lymphoproliferative syndrome and 1 boy with X-linked hyperimmunoglobulin-M syndrome. Pretransplant cytoreduction and posttransplant graft-versus-host prophylaxis were given. Hematopoietic engraftment and correction of the genetic defects were documented by molecular techniques. Two years after transplantation, all 3 patients have normal immune systems. These reports support the wider use of banked partially matched cord blood for transplantation in primary immunodeficiencies.

Background: It has been proposed that exposure to long-term spaceflight conditions (stress, isolation, sleep disruption, containment, microbial contamination, and solar radiation) or to ground-based models of spaceflight will alter human immune responses, but specific antibody responses have not been fully evaluated., Objective: We sought to determine whether exposure to the 8-month Antarctic winter-over model of spaceflight would alter human antibody responses., Methods: During the 1999 Australian National Antarctic Research Expeditions, 11 adult study subjects at Casey, Antarctica, and 7 control subjects at Macquarie Island, sub-Antarctica, received primary and secondary immunizations with the T cell-dependent neoantigen bacteriophage phi X-174. Periodic plasma samples were analyzed for specific antibody function., Results: All of the subjects from Casey, Antarctica, cleared bacteriophage phi X-174 normally by 1 week after primary immunization, and all had normal primary and secondary antibody responses, including immunologic memory amplification and switch from IgM to IgG antibody production. One subject showed a high normal pattern, and one subject had a low normal pattern. The control subjects from Macquarie Island also had normal immune responses to bacteriophage phi X-174., Conclusions: These data do not support the hypothesis that de novo specific antibody responses of subjects become defective during the conditions of the Antarctic winter-over. Because the Antarctic winter-over model of spaceflight lacks the important factors of microgravity and solar radiation, caution must be used in interpreting these data to anticipate normal antibody responses in long-term spaceflight.

Background: CD11a/CD18 comprise subunits of leukocyte function associated antigen (LFA-1), a T-cell surface molecule important in T-cell activation, T-cell emigration into skin, and cytotoxic T-cell function., Objective: We explored the immunobiologic and clinical effects of treating moderate to severe psoriasis vulgaris with a single dose of humanized monoclonal antibody against CD11a (hu1124)., Methods: This was an open label study with a single dose of hu1124 at doses of 0.03 to 10 mg/kg. Clinical (Psoriasis Area and Severity Index [PASI]) and immunohistologic parameters (epidermal thickness, epidermal and dermal T-cell numbers, and keratinocyte intercellular adhesion molecule 1 [ICAM-1] expression) were followed., Results: Treatment with hu1124, at doses higher than 1.0 mg/kg (group III), completely blocks CD11a staining for at least 14 days in both blood and psoriatic plaques. At 0.3 to 1.0 mg/kg, T-cell CD11a staining was completely blocked; however, blockade lasted less than 2 weeks (group II). Only partial saturation of either blood or plaque cellular CD11a was observed at doses of hu1124 between 0.01 and 0.1 mg/kg (group I). This pharmacodynamic response was accompanied by decreased numbers of epidermal and dermal CD3(+) T cells, decreased keratinocyte and blood vessel expression of ICAM-1, and epidermal thinning. Statistically significant drops in PASI compared with baseline were observed in group II patients at weeks 3 and 4 and in group III patients at weeks 2 through 10. No significant drop in PASI score was observed in group 1. Adverse events were mild at doses of 0.3 mg/kg or less and included mild chills, abdominal discomfort, headache, and fever. At a single dose of 0.6 mg/kg or higher, headache was the most common dose-limiting toxicity observed., Conclusion: Targeting CD11a may improve psoriasis by inhibiting T-cell activation, T-cell emigration into the skin, and cytotoxic T-cell function.

We describe 5 children from 2 families with mutations in the CD40 ligand (CD40L) gene leading to absent expression of CD40L on activated CD4 cells. All subjects presented with interstitial pneumonia with low serum IgG and normal serum IgM. One child had normal and one child had elevated serum IgA. Four had confirmed Pneumocystis carinii pneumonia. In spite of intravenous immunoglobulin treatment yielding therapeutic serum immunoglobulin levels, 3 children had enteroviral encephalitis. When assessed by flow cytometry, the 3 surviving affected male children had absent CD40L expression on activated CD4(+) T cells. The affected children from both families were shown to have the same single nucleotide insertion (codon 131) resulting in frameshift and early termination within exon 4 (extracellular domain). This observation demonstrates that persistent enteroviral infection is not only observed in X-linked agammaglobulinemia but may also occur in patients with X-linked hyper IgM syndrome.

We examined T-cell proliferation in five patients with X-linked hyper-IgM syndrome (XHIM), using a panel of antigens and lectins. All patients had impaired antigen-induced proliferation, whereas their lectin responses were normal. Thus, in addition to severely depressed antibody responses, patients with XHIM have a defect in antigen-specific T-cell proliferation, which may explain their susceptibility to pathogens such as Pneumocystis carinii.

Objective: To determine primary and secondary antibody responses in children with hypogammaglobulinemia attributed to corticosteroid use., Results: In seven patients with steroid-dependent asthma and significant hypogammaglobulinemia (IgG concentration, 275 to 443 mg/dl), antibody responses to protein and polysaccharide antigens were shown to be normal, as were primary and secondary responses to a neoantigen, bacteriophage phi X174., Conclusions: Patients with asthma, and with hypogammaglobulinemia resulting from steroid therapy, have normal humoral immunity, and immunoglobulin replacement therapy is not indicated.

Adenosine deaminase (ADA) deficiency is the cause of about one third of the autosomal recessively inherited cases of severe combined immunodeficiency. Disease severity in ADA deficiency is variable, presumably related in part to heterogeneity in the genotypes causing the disease. We now report on two children in a single family with ADA deficiency who presented with distinct clinical courses. One child presented with severe immunodeficiency and recurrent infections that led to the diagnosis of severe combined immunodeficiency and ADA deficiency at 7 months of age. The older child, who was diagnosed at 3 years of age (after the diagnosis of the younger child), did not have a history of serious or opportunistic infections. Although she was lymphopenic, immune responsiveness was intact, in terms of antibody production, delayed-type hypersensitivity, and in vitro T-cell function. The difference in clinical course in these two siblings is an important observation and demonstrates that the phenotypic expression of ADA deficiency can vary within a family, even in a situation in which protective isolation from infectious pathogens was not a factor in causing the milder course. These observations indicate that expression of disease severity in ADA deficiency may depend to a significant degree on environmental factors and/or on heterogeneity at other genetic loci, which may regulate or modify the expression of the ADA gene or the activity of its product. Furthermore, these observations highlight the importance of recognizing patients with ADA deficiency who present with less severe disease and support the impression that functional immunity in patients with the "late-onset" form of ADA deficiency can deteriorate over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Specific antibody production was assessed in six young children with the acquired immune deficiency syndrome (AIDS). All patients were immunized with bacteriophage phi X 174, a T cell-dependent neoantigen. In addition, antibody responses to pneumococcal vaccine and tetanus toxoid, lymphocyte responses to mitogens, and serum immunoglobulin levels were determined. Polyclonal hypergammaglobulinemia was documented in three patients. Responses to bacteriophage phi X 174 were abnormal in all patients: primary responses were blunted, secondary responses were markedly decreased, and the class switch (IgM-IgG) was absent in five of six patients. Antibody formation to pneumococcal vaccine and tetanus toxoid was also diminished. Lymphocyte mitogenic responses to phytohemagglutinin, concanavalin A, pokeweed mitogen, and staphylococcal Cowan A were generally decreased. These findings confirm that pediatric patients with AIDS have significant abnormalities in humoral immunity. Dysfunction of both T cells and B cells plays a role in the resultant poor specific antibody production.

Antibody responses to bacteriophage phichi 174 were studied in 17 institutionalized patients with trisomy 21 and in six mentally retarded control patients with normal karyotype. Primary antibody response was significantly impaired in 11 of the 17 patients. Secondary immune response was normal in one, moderately impaired in seven, and very low in nine patients. Tertiary immunization further differentiated the two groups: those with moderately impaired secondary immune responses developed normal serum titers of predominantly IgG antibody; patients with low secondary immune responses had extemely impaired tertiary immune responses consisting mainly of serum IgM antibody.

One hundred and twelve well-studied patients with a prior diagnosis of juvenile rheumatoid arthritis were differentiated into seven clinically distinct subgroups, including a group in whom recognizable ankylosing spondylitis had developed by time of follow-up. An apparent increased prevalence of HLA-B27 in the entire series (26%) was clearly related to its increased prevalence in only two subgroups: patients whose disease had progressed to overt ankylosing spondylitis (five of five patients) and boys with pauciarticular arthritis whose disease would be consistent with early ankylosing spondylitis (11 of 18 patients). There were no significant associations of B27 with systemic onset JRA, polyarticular JRA, pauciarticular JRA in girls, or JRA with chronic iridocyclitis. The only other significant alterations found were increased prevalences of HLA-A2 and HLA-BW15 in patients with polyarticular disease without identifiable rheumatoid factor. This study emphasizes that the clinical disorders included under the category of juvenile rheumatoid arthritis represent more than a single disease and that this heterogeneity must be considered in interpreting studies such as those of histocompatibility typing.

We studied two patients with delayed umbilical cord detachment, recurrent bacterial infections, inability to form pus, rapidly progressive periodontitis, and persistent leukocytosis. The phagocytes of both patients were strikingly abnormal in their ability to adhere to surfaces. The adherence of polymorphonuclear leukocytes to endotoxin-coated glass coverslips, glass beads, or nylon wool was markedly reduced. Scanning electron microscopy of the few adherent polymorphonuclear leukocytes from both patients showed a failure to flatten and form fine pseudopods. In vivo polymorphonuclear leukocyte and monocyte chemotaxis assessed by skin window and skin chamber methods was dramatically impaired, and in vitro chemotaxis was severely depressed. Chemiluminescence of zymosan- but not phorbol-stimulated polymorphonuclear leukocytes was markedly reduced. Allogeneic polymorphonuclear leukocytes transfused into these patients functional normally, indicating that the defect is intrinsic to the cells and not a secondary phenomenon. A 180-kilodalton glycoprotein normally present in the particulate fraction of polymorphonuclear leukocytes was found to be completely absent in Patient 1 and present in low concentration in Patient 2. We postulate that the glycoprotein deficiency interferes with the migration of polymorphonuclear leukocytes from the bloodstream into the interstitial space and to the site of infection.