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To determine the potential diagnostic and therapeutic targets of Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS).We selected the GSE11783, GSE57560 and GSE621 datasets from the GEO database and merged them. R software was used to screen differentially expressed genes (DEGs) between IC/BPS and normal bladder tissues. The "String" online tool is used to analyze DEGs interaction and functional protein enrichment. CIBERSORT online tool was used to analyze the infiltration of immune cells. In addition, we verified the function of BTK in IC/BPS at the clinical samples and cells level.Bioinformatics analysis revealed that 5 genes were significantly overexpressed in IC/BPS, and the protein-protein interaction diagram showed that BTK was a critical link between these five proteins. At the same time, functional enrichment showed that they were significantly related to innate immunity. Immunoinfiltration showed that mast cell resting in IC/BPS was significantly higher. IHC staining of clinical samples showed that the mast cell markers Tryptase and BTK were highly expressed in IC/BPS tissues. At the cell level, knockdown of BTK inhibited proliferation, migration, invasion, and degranulation of mast cells.This study provides a new perspective for understanding the molecular mechanisms involved in IC/BPS and suggests that BTK may be a target for treating IC/BPS.

Quantitation of urinary metabolites of histamine, prostaglandin D

Mast cell activation (MCA) is common and occurs in a number of pathologic conditions, including IgE-dependent and independent allergic reactions, atopic disorders, autoimmune processes, and mastocytosis. In a subset of patients, no underlying disease and no known trigger of MCA are found. When the symptoms are severe, systemic, and recurrent, and accompanied by a diagnostic increase in the serum tryptase level or other mast cell mediators, an MCA syndrome (MCAS) may be diagnosed. In these patients, the symptoms typically respond to drugs suppressing MCA, mediator production in mast cells, or mediator effects. In each case, diagnostic consensus criteria must be fulfilled to diagnose MCAS. In other patients, MCA may be local, less severe, or less acute, or may be suspected but not confirmed, so that the diagnostic criteria of MCAS are not fulfilled. In these patients, it may be difficult to prove MCA, for example, by measuring multiple mast cell mediators or basophil activation, the latter as a surrogate of IgE-dependent hypersensitivity. However, validated diagnostic criteria for implicating suspected MCA behind such conditions are lacking, even if some of these conditions have recently been assigned to an International Classification of Diseases-10-Clinical Modification code (ICD-10-CM). In this article, we discuss diagnostic features and criteria and propose a ICD-10-CM–adjusted classification for disorders associated with MCA, herein referred to as MCA disorders (MCADs), with special emphasis on the delineation between confirmed MCAS, MCAD not fulfilling MCAS criteria, and suspected MCAD that is not present. In addition, we discuss the discrimination between overt MCAD and predisposing conditions, such as atopic states, mastocytosis, and hereditary alpha tryptasemia., T.G. was supported by grants from the Konsul TH C Bergh Foundation and the Stockholm County Council Research Funds (ALF), Sweden. M.C.C., J.J.L, and D.D.M. were supported by the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH). The content is solely the responsibility of the authors and does not represent the official views of the NIH. P.V. was supported by the Austrian Science Fund (FWF; projects P32470-B and F4704-B20).

Indolent systemic mastocytosis (ISM) has a favorable prognosis and normal life expectancy. However, many patients suffer from mast cell (MC) mediator-related symptoms, which significantly affect quality of life (QoL). Cutaneous, gastrointestinal, and neurological complaints, musculoskeletal pain, and the presence of skin lesions, anaphylaxis, and osteoporosis are the main symptoms and signs in ISM and must be assessed in all patients before and during treatment. Validated mastocytosis-specific patient-reported outcome measures (PROMs) should be used for this purpose. Serum tryptase and KIT D816V allele burden are recommended as secondary outcome parameters, noting that they do not reflect the severity of signs, symptoms, and related QoL impairment, but indirectly express MC burden. Changes from baseline of 90%, 60%, and 30% indicate complete response >90%, major response 60% to 90%, partial response 30% to 60%, and no response, M. C. Carter, J. J. Lyons, and D. D. Metcalfe were supported by the Division of Intramural Research, National Institutes of Allergic and Infectious Diseases, and National Institutes of Health. M. Niedoszytko was supported by the Medical University of Gdansk grant 02-0141/07/231. P. Valent was supported by the Austrian Science Fund (FWF) grant # P32470-B.

Anaphylaxis is the most acute and life-threatening manifestation of allergic disorders. Currently, there is a need to improve its medical management and increase the understanding of its molecular mechanisms. This study aimed to quantify the extravasation underlying human anaphylactic reactions and propose new theragnostic approaches.Molecular determinations were performed in paired serum samples obtained during the acute phase and at baseline from patients presenting with hypersensitivity reactions. These were classified according to their severity as Grades 1, 2 and 3, the two latter being considered anaphylaxis. Tryptase levels were measured by ImmunoCAP, and serum protein concentration was quantified by Bradford assay. Human serum albumin (HSA) and haemoglobin beta subunit (HBB) levels were determined by Western blot and polyacrylamide gel electrophoresis, respectively.A total of 150 patients were included in the study. Of them, 112 had experienced anaphylaxis (83 and 29 with Grade 2 and 3 reactions, respectively). Tryptase diagnostic efficiency substantially improved when considering patients' baseline values (33%-54%) instead of the acute value threshold (21%). Serum protein concentration and HSA significantly decreased in anaphylaxis (p .0001). HSA levels dropped with the severity of the reaction (6% and 15% for Grade 2 and 3 reactions, respectively). Furthermore, HBB levels increased during the acute phase of all hypersensitivity reactions (p .0001).For the first time, the extravasation underlying human anaphylaxis has been evaluated based on the severity of the reaction using HSA and protein concentration measurements. Additionally, our findings propose new diagnostic and potential therapeutic approaches for this pathological event.

Advanced systemic mastocytosis (AdvSM) is a rare myeloid neoplasm associated with poor overall survival (OS). This study (NCT04695431) compared clinical outcomes between patients with AdvSM treated with avapritinib in the Phase 1 EXPLORER (NCT0256198) and Phase 2 PATHFINDER (NCT03580655) trials (N = 176) and patients treated with best available therapy (BAT; N = 141). A multi-center, observational, retrospective chart review study was conducted at six study sites (four European, two American) to collect data from patients with AdvSM who received BAT; these data were pooled with data from EXPLORER and PATHFINDER. Comparisons between outcomes of OS, duration of treatment (DOT), and maximum reduction in serum tryptase were conducted between the treatment cohorts, with adjustment for key covariates. The results indicated that the avapritinib cohort had significantly better survival (adjusted hazard ratio (HR) (95% confidence interval (CI)): 0.48 (0.29, 0.79); p = 0.004) and significantly longer DOT (HR: 0.36 (0.26, 0.51); p p

Patients with systemic mastocytosis often have symptoms of mast cell activation, which is associated with elevated levels of urinary mast cell mediator metabolites. Patients with hereditary α-tryptasemia (HαT) may present with symptoms of mast cell activation. Whether levels of mast cell mediators are elevated in this patient population is not known.The purpose of this study was to determine whether patients with HαT and symptoms of mast cell activation have elevated levels of urinary mediators and compare the levels with those in patients with systemic mastocytosis.We retrospectively analyzed mast cell mediators in 63 patients with a confirmed diagnosis of HαT, 20 patients with a confirmed diagnosis of indolent systemic mastocytosis (ISM), and 23 healthy controls. All patients were referred to the Brigham and Women's Hospital Mastocytosis Center or the Mayo Clinic for evaluation of mast cell activation disorders.Our population was predominantly female (85.7%) with an average age of 53.8 years. The average baseline serum tryptase level was significantly higher in patients with ISM than in those with HαT (65.9 vs 19.3 ng/mL [P lt; .01]). When compared with patients with HαT, those with ISM had statistically significant increases in their levels of urinary N-methylhistamine (P lt; .01) and 2,3-dinor-11β-prostaglandin F2α (P lt; .05).Patients with symptomatic HαT do not have elevations of mast cell urinary metabolites, suggesting that granule- and membrane-derived mediators may not drive symptoms in HαT.

Sex discrepancies have been reported in chronic rhinosinusitis (CRS), but limited data exist exploring sex-specific biological processes and sinonasal quality of life.Prospective cohort.Academic medical center.Demographics, clinical data, and sinonasal mucus were collected from patients with CRS presenting for surgical consideration over a 5-year period. A random forest model and linear regression were used to assess predictor variables for the 22-item Sino-Nasal Outcome Test (SNOT-22) and subdomains. Enzyme-linked immunosorbent assays were used to measure substance P and tryptase in a subset of mucus samples to explore biological differences by sex.In total, 520 patients were studied (mean age 48.3 years, 50.9% female). Males were older (50.1 vs 46.6 years,Sex differences exist in CRS disease manifestations and presentation for surgical consideration. Detection of mucus (substance P and tryptase) was reliable, but in this exploratory study, we were not able to establish neurogenic or allergic inflammatory processes as a large source of differential disease features between sexes.

There is strong evidence of an association between severe anaphylaxis, especially hymenoptera venom induced, and mast cell (MC) disorders. It has been thought that intrinsic abnormalities in MCs, including the presence of the activating KIT D816V mutation in mastocytosis or of genetic trait, hereditary alpha-tryptasemia, may influence susceptibility to severe anaphylaxis. This article evaluates the potential mechanisms leading to severe MC activation, as well as the differential diagnosis of and range of symptoms attributable to MC mediator release. Also, we offer a global classification for disorders related to MC activation.

The diagnosis of mast cell activation syndrome (MCAS) is defined by 3 criteria: (1) typical clinical signs and symptoms of acute, recurrent (episodic), and systemic mast cell activation (MCA); (2) increase in tryptase level to >20% + 2 ng/mL within 1-4 hours after onset of the acute crisis; and (3) response of MCA symptoms to antimediator therapy. Classification of MCAS requires highly sensitive and specific methodological approaches for the assessment of clonal bone marrow mast cells at low frequencies. The Spanish Network on Mastocytosis score has been used successfully as a predictive model for selecting MCAS candidates for bone marrow studies based on a high probability of an underlying clonal mast cell disorder. In this article, we propose a diagnostic algorithm and focus on the practical evaluation and management of patients with suspected MCAS. Key words: Anaphylaxis. Antimediator therapy. Mast cell activation syndrome. Mast cell mediator release–related symptoms. Tryptase.

Hymenoptera venom anaphylaxis is the most frequent cause of anaphylaxis and responsible for about 20% of all fatal anaphylaxis cases in adults. We report two cases of fatal hymenoptera venom anaphylaxis with undiagnosed underlying mastocytosis and review the risk factors for severe or fatal hymenoptera venom anaphylaxis, as well as the specificities of its association with mastocytosis. As hymenoptera venom allergic patients with underlying clonal mast cell disorder generally lack typical skin lesions of mastocytosis, its diagnosis can easily be missed, underscoring the importance and need for diagnostic strategies in order to correctly identify these patients. Predominant cardiovascular symptoms in the absence of urticaria or angioedema following an insect sting are suggestive of underlying clonal mast cell disorder, and should be distinguished from panic attack or vasovagal syncope. Similarly, an unexplained syncope or an "idiopathic" anaphylaxis might reveal mastocytosis or hereditary alpha-tryptasemia. Acute and basal serum tryptase measurements should always be integrated in the diagnostic work-up of an insect sting reaction or unexplained syncope or shock of any origin.

Background Pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) and vasoactive intestinal polypeptide can provoke cluster headache attacks in up to half of cluster headache patients in their active phase. At present, it is unknown whether provoked attacks are mediated via calcitonin gene-related peptide or mast cell activation. Methods All enrolled patients with cluster headache were randomly allocated to receive a continuous infusion of either PACAP38 (10 pmol/kg/min) or vasoactive intestinal polypeptide (8 pmol/kg/min) over 20 min. We collected clinical data and measured plasma levels of calcitonin gene-related peptide and markers of mast cell activation (tryptase and histamine) at fixed time points: at baseline (T0), at the end of the infusion (T20), 10 min after the infusion (T30), and 70 min after the infusion (T90). Results Blood was collected from episodic cluster headache patients in active phase (n = 14), episodic cluster headache patients in remission (n = 15), and chronic cluster headache patients (n = 15). At baseline, plasma levels of calcitonin gene-related peptide, tryptase, and histamine were not different among the three study groups. Plasma levels of calcitonin gene-related peptide ( p = 0.7074), tryptase ( p = 0.6673), or histamine ( p = 0.4792) remained unchanged during provoked attacks compared to attack-free patients. Conclusion Cluster headache attacks provoked by either PACAP38 or vasoactive intestinal polypeptide were not accompanied by alterations of plasma calcitonin gene-related peptide, tryptase or histamine. The provoked attacks may not be mediated by calcitonin gene-related peptide or mast cell activation. Trial Registration: The study is registered at ClinicalTrials.gov (NCT03814226).

Introduction: Idiopathic anaphylaxis (IA) is a diagnosis of exclusion and is based on the inability to identify a causal relationship between a trigger and an anaphylactic event, despite a detailed patient history and careful diagnostic assessment. The prevalence of IA among the subset of people who experienced anaphylaxis is challenging to estimate and varies widely, from 10 to 60%; most commonly noted is ∼20% in the adult anaphylactic population. Comorbid atopic conditions, such as food allergy, allergic rhinitis, and asthma, are present in up to 48% of patients with IA. Improved diagnostic technologies and an increased understanding of conditions that manifest with symptoms associated with anaphylaxis have improved the ability to determine a more accurate diagnosis for patients who may have been initially diagnosed with IA. Methods: Literature search was conducted on PubMed, Google Scholar and Embase. Results: Galactose-α-1,3-galactose (α-gal) allergy, mast cell disorders, and hereditary a-tryptasemia are a few differential diagnoses that should be considered in patients with IA. Unlike food allergy, when anaphylaxis occurs within minutes to 2 hours after allergen consumption, α-gal allergy is a 3‐6-hour delayed immunoglobulin E‐mediated anaphylactic reaction to a carbohydrate epitope found in red meat (e.g., beef, lamb, pork). The more recently described hereditary α-tryptasemia is an inherited autosomal dominant genetic trait caused by increased germline copies of tryptase human gene alpha-beta 1 (TPSAB1), which encodes α tryptase and is associated with elevated baseline serum tryptase. Acute management of IA consists of carrying an epinephrine autoinjector to be administered immediately at the first signs of anaphylaxis. Long-term management for IA with antihistamines and other agents aims to potentially reduce the frequency and severity of the anaphylactic reactions, although the evidence is limited. Biologics are potentially steroid-sparing for patients with IA; however, more research on IA therapies is needed. Conclusion: The lack of diagnostic criteria, finite treatment options, and intricacies of making a differential diagnosis make IA challenging for patients and clinicians to manage.

Summary Background Tezepelumab is a human monoclonal antibody that blocks the activity of thymic stromal lymphopoietin (TSLP), an epithelial cell-derived cytokine. In phase 2b and 3 studies, tezepelumab significantly reduced exacerbations versus placebo in patients with severe uncontrolled asthma, irrespective of baseline levels of type 2 inflammatory biomarkers. We investigated the mechanism of action of tezepelumab by assessing its effects on airway inflammatory cells, airway remodelling, and airway hyperresponsiveness. Methods CASCADE was an exploratory, double-blind, randomised, placebo-controlled, parallel-group, phase 2 study done in 27 medical centres in Canada, Denmark, Germany, the UK, and the USA. Adults aged 18–75 years with uncontrolled, moderate-to-severe asthma were randomly assigned (1:1) to receive tezepelumab 210 mg or placebo administered subcutaneously every 4 weeks for a planned 28 weeks, extended to up to 52 weeks if COVID-19-related disruption delayed participants' end-of-treatment assessments. Randomisation was balanced and stratified by blood eosinophil count. The primary endpoint was the change from baseline to the end of treatment in the number of airway submucosal inflammatory cells in bronchoscopic biopsy samples. Eosinophils, neutrophils, CD3+ T cells, CD4+ T cells, tryptase+ mast cells, and chymase+ mast cells were evaluated separately. This endpoint was also assessed in subgroups according to baseline type 2 inflammatory biomarker levels, including blood eosinophil count. Airway remodelling was assessed via the secondary endpoints of change from baseline in reticular basement membrane thickness and epithelial integrity (proportions of denuded, damaged, and intact epithelium). Exploratory outcomes included airway hyperresponsiveness to mannitol. All participants who completed at least 20 weeks of study treatment, had an end-of-treatment visit up to 8 weeks after the last dose of study drug, and had evaluable baseline and end-of-treatment bronchoscopies were included in the primary efficacy analysis. All participants who received at least one dose of study drug were included in the safety analyses. This study is registered with ClinicalTrials.gov, NCT03688074. Findings Between Nov 2, 2018, and Nov 16, 2020, 250 patients were enrolled, 116 of whom were randomly assigned (59 to tezepelumab, 57 to placebo). 48 in the tezepelumab group and 51 in the placebo group completed the study and were assessed for the primary endpoint. Treatment with tezepelumab resulted in a nominally significantly greater reduction from baseline to the end of treatment in airway submucosal eosinophils versus placebo (ratio of geometric least-squares means 0·15 [95% CI 0·05–0·41]; nominal p 0·10). In assessment of secondary endpoints, there were no significant differences between treatment groups in reticular basement membrane thickness and epithelial integrity. In an exploratory analysis, the reduction in airway hyperresponsiveness to mannitol was significantly greater with tezepelumab versus placebo (least-squares mean change from baseline in interpolated or extrapolated provoking dose of mannitol required to induce ≥15% reduction in FEV1 from baseline: tezepelumab 197·4 mg [95% CI 107·9 to 286·9]; placebo 58·6 mg [−30·1 to 147·33]; difference 138·8 [14·2 to 263·3], nominal p=0·030). Adverse events were reported in 53 (90%) patients in the tezepelumab group and 51 (90%) patients in the placebo group, and there were no safety findings of concern. Interpretation The improvements in asthma clinical outcomes observed in previous studies with tezepelumab are probably driven, at least in part, by reductions in eosinophilic airway inflammation, as shown here by reduced airway eosinophil counts regardless of baseline blood eosinophil count. Tezepelumab also reduced airway hyperresponsiveness to mannitol, indicating that TSLP blockade might have additional benefits in asthma beyond reducing type 2 airway inflammation. Funding AstraZeneca and Amgen.

[Objective]: Mast cell (MC) activation (MCA) defines the mechanism by which certain patients have symptoms owing to the effect of a wide range of mediators released from MCs upon their activation, when triggered by different stimuli. When these symptoms are severe and recurrent, the diagnosis of MCA syndrome (MCAS) might be considered. Here, we review the relevant aspects related to the pathogenesis of MCAS, with special emphasis on the prevalence and diagnostic relevance of KIT mutations., [Data Sources]: PubMed was searched between 1980 and 2021 using the following terms: mast cell activation syndromes, mast cell activation, anaphylaxis, KIT mutations, KIT D816V, indolent systemic mastocytosis, bone marrow mastocytosis, cutaneous mastocytosis, IgE anaphylaxis, and idiopathic anaphylaxis., [Study Selections]: Only articles published in English were selected based on their relevance to MCAS or severe and recurrent anaphylaxis., [Results]: MCAS can be classified as clonal MCAS and nonclonal MCAS depending on the presence vs absence of an underlying KIT mutation (mostly KIT D816V), respectively. In contrast to clonal MCAS in which MCA is associated with a primary MC disorder (ie, primary MCAS) such as mastocytosis or monoclonal MCAS, nonclonal MCAS can be secondary to known or unidentified triggers (ie, secondary and idiopathic MCAS, respectively)., [Conclusion]: The clinical heterogeneity and complexity of the molecular assays needed for the study of patients with MCAS might lead to misdiagnosis, particularly when patients are evaluated at nonspecialized centers. Thus, referral of patients having clinical manifestations suggestive of MCAS to reference centers on mastocytosis and MC diseases is strongly recommended., This work was supported by grants from the Instituto de Salud Carlos III (Madrid, Spain), Fondos Europeos de Desarrollo Regional (reference numbers: PI19/01166 and Centro de Investigación Biomédica en Red de Cáncer, CB16/12/00400), Fundación Española de Mastocitosis (Madrid, Spain; reference number: FEM2021-SAM), and Asociación Española de Pacientes con Mastocitosis y otras Enfermedades Relacionadas (Madrid, Spain; reference number: AEDM2019-SAM).

Dysregulated mast cell-mediated inflammation and/or activation have been linked to a number of human diseases, including asthma, anaphylaxis, chronic spontaneous urticaria, and mast cell activation syndromes. As a major mast cell granule protein, tryptase is a biomarker commonly used in clinical practice to diagnose mast cell-associated disorders and -mediated reactions, but its mechanistic roles in disease pathogenesis remains incompletely understood. Here, we summarize recent advances in the understanding of human tryptase genetics and the effects that different genetic composition may have on the quaternary structure of tetrameric mature tryptases. We also discuss how these differences may impact clinical phenotypes including allergic inflammation, immediate hypersensitivity, and others seen in patients with mast cell-associated disorders. With the increased application of next-generation sequencing, we foresee that human genetic approaches will be a major focus of understanding human tryptase functions in various human mast cell disorders and in new therapeutic development.

Mast cells (MCs) are immune cells that are distributed in all tissues throughout the body, and their cytoplasm is rich in granules containing histamine and tryptase. When MCs recognize antigens through IgE bound to FceRI, they release these mediators by degranulation. Because degranulation induces various type I allergic reactions, such as anaphylactic shock and hay fever, elucidation of the control mechanism of degranulation is important to the development of a therapeutic strategy for allergic diseases. It is known that the antigen-induced degranulation response is fine-tuned by various humoral factors via the activation of G protein-coupled receptors. We found that extracellular ATP enhanced antigen-dependent and -independent MC degranulation via activation of ionotropic P2X4 receptors. P2X4 receptor activation itself had no effect on MC degranulation, but significantly enhanced antigen-triggered degranulation. Stimulation of the P2X4 receptor potentiated the FceRI-mediated tyrosine kinase signaling cascade. In addition to antigen-induced responses, P2X4 receptor signaling also affected antigen-independent MC responses. Thus, co-stimulation of ATP and Gi-coupled receptor agonists, such as prostaglandin E2 (PGE2) and adenosine, resulted in synergistic degranulation. The significance of P2X4 receptor signaling in allergic and inflammatory responses in vivo was confirmed by impaired responses of antigen-induced passive anaphylaxis and PGE2-induced increases in vascular permeability in P2rx4 knockout mice compared to that of wild-type mice. These results suggest that the P2X4 receptor is a potential therapeutic target for both antigen-dependent and -independent allergic reactions.

Head and neck squamous cell carcinoma (HNSCC) is one of the most frequent and aggressive neoplasms of this anatomical region. Many studies evaluated the neoplastic cells, but few works focused on the tumor microenvironment. In the present study, we investigated the distribution and mast cell density (MCD) in malignant and premalignant lesions of the oral cavity, tongue, pharynx, and larynx. There were analyzed 52 specimens of HNSCC, and 15 biopsies taken from patients with dysplasia. Results were compared with those found in a control group of 10 biopsies of oral mucosa from patients with inflammatory diseases. Slides stained with Hematoxylin-Eosin were used for the histopathological diagnosis and grade, and mast cells (MCs) were identified by immunohistochemistry, using anti-MC tryptase. MCs were counted using a method similar to that proposed for microvessel density. We found a significant increase in the number of MCs from the normal oral mucosa until overt carcinoma. Unlike normal tissues, in HNSCC, many MCs were found between tumor cells. We found no relationship between MCs and blood vessels in the tumor area. A significant statistical correlation was found between dysplastic and malignant tumors, but not between tumors with a different grade. Also, it was not found relationship between MCD and the anatomical location of the tumor. Based on these results, we believe that MCD evaluated by anti-MC tryptase is an independent factor of prognosis and reflects an unfavorable outcome.

Introduction: Placental pathology and pregnancy complications are associated with unfavorable regulation of the maternal immune system. Although much research has been performed towards the role of immune cells like macrophages and T cells in this context, little is known about the presence and function of mast cells (MC). MC can be sub classified in tryptase-positive (MCT) and tryptase- and chymase-positive (MCTC). This study investigates the presence of MC in the decidua of pregnancies complicated by fetal growth restriction (FGR) and stillbirth (SB).Methods: Placental tissue from FGR (n = 250), SB (n = 64) and healthy pregnancies (n = 42) was included. Histopathological lesions were classified according to the Amsterdam Placental Workshop Group criteria. Tissue sections were stained for tryptase and chymase. Decidual MC were counted manually, and the results were expressed as number of cells/mm2 decidual tissue.Results: A significant lower median number of MCTC was found in the decidua of FGR (0.40 per mm2; p < 0.001) and SB (0.51 per mm2; p < 0.05) compared to healthy controls (1.04 per mm2). No difference in MCT number (1.19 per mm2, 1.88 per mm2 and 1.37 per mm2 respectively) was seen between the groups. There was no difference in number of MCT and MCTC between placental pathological lesions.Discussion: Our findings suggest a shift in decidual MC balance towards MCT in pregnancy complications. No difference in numbers of MC subtypes was found to be related to histopathologic lesions.

Medical psychiatry acquires more prominence in the biological field by new anatomical insights into the wrappings of the brain: meninges, but also Meningo-Calvarial Channels (MCCs) connecting the former with the bone marrows' also neuronally steered, functions. The skull-bone's meningeal arteries through migrating and orchestrating mast cells within a framework stressing their relations with arteries (Treviranus 2012-21) could explain enigmatic phenomena like migrainous and post-injury Cortical Spreading Depressions (CSD) or the Reversible Cerebral Vasoconstriction Syndrome (RCVS) escalating to "PRES". The skull might be accessed along chronic (para-)infectious paths resulting in Skull Bone Osteomyelitis (SBO) from the ear-nose-throat, dental and other microbiomes. Such paths seem promoted by compromised innate immune defenses: by "Mendelian" susceptibility, and/or acquired anti-INF-γ- or other auto-immunity or various microbial "Trojans" of e. g. meningeal myelo- and lymphocytes. These interact e. g. from the calvarial marrow niches onward. Hereby competing local and "intentional" intruding mast cells - by disturbing (or ingeniously boosting) cortical development and functioning - acquire relevance by interacting with arteries (Treviranus 2018, 2021). This predicts findings in behavior (FitzpatrickMorrow 2017) an "aortal" arterial biomechanical foundation of parasympathetic reverse arterio-intramural cerebro-interstitial drainage by CIMURAF/IPAD-2.0 (Treviranus 2018-21). Here the recent physiological re-conceptions of the skull illuminate own case histories through a gamut of possibly relevant neuro(-surgico)-psychiatric challenges. Among these meningo-cerebral immune, vasospastic, and cystic processes some generate broad "experiential" hallucinations, which may slowly transit to true psychoses through "perfect crime lesions" of neurons and glia by tryptase-armed mast cells descending into parenchyma often congested by "push-back". These emerging hypotheses coalesce in advancing an integrative macro-medical psychiatry and even the pathography of Van Gogh and Mozart stressing the benign and creative roles of mast cells.

Advanced systemic mastocytosis (AdvSM) is a rare hematologic neoplasm with poor overall survival that is characterized by an accumulation of neoplastic mast cells in various tissues and organs. Although driven by KIT D816V in 95% of cases, the heterogeneous symptom presentation of AdvSM patients may contribute to a lengthy diagnostic journey.To characterize the symptomology of AdvSM patients reported by oncologists at the initial patient encounter in a community-based setting.This was a cross-sectional survey study conducted from August-November 2021. Community oncologists affiliated with Integra Connect were asked to complete a structured eCRF on referral patterns, patient signs and symptoms at initial visit, approach to diagnosis, and ongoing disease management for patients they diagnosed or treated with AdvSM in the prior 24 months.Community oncology practices affiliated with Integra Connect.Twenty-eight community oncologists provided data on 55 AdvSM patients. Twenty-one had managed 2 or more AdvSM patients in the previous 3 years. Mean patient age was 56 years; 55% were female. Comorbid conditions included cardiovascular disease (38%), diabetes (38%), GERD (29%), and COPD/asthma (25%). AdvSM patients were referred to participating oncologists by primary care physicians (33%), immunologists (28%), dermatologists (11%), another oncologist (11%), rheumatologists (7%), and other specialists (9%). 93% of oncologists reported bone marrow biopsy as critical in making an AdvSM diagnosis and indicated that elevated serum tryptase (64%) and detection of KIT D816V (56%) were also important factors in making the AdvSM diagnosis. Cutaneous, gastrointestinal (GI), neuropsychiatric, and musculoskeletal signs and symptoms were common. The most common symptoms reported were pruritis (65%), maculopapular cutaneous mastocytosis (62%), flushing (60%), nausea (58%), and bloating and diarrhea (52%). Allergic reactions (40%), anaphylaxis (24%), dyspnea (35%), anxiety (49%), and fatigue (62%) were also frequently reported at the initial visit.This study shows that AdvSM patients receiving care in a community-based oncology setting are referred to oncologists from a variety of different specialties with a range of disease-related symptoms and multitude of comorbid conditions. Improving awareness of the clinical presentation and diagnostic strategies for AdvSM patients may expedite disease recognition, diagnosis, and treatment initiation.

Advanced SM (AdvSM) comprises 3 subtypes: aggressive SM (ASM), SM with an associated hematologic neoplasm (SM-AHN), and mast cell leukemia (MCL). The patterns of organ damage, which have been defined by WHO, IWG, and modified IWG (mIWG) criteria, across the spectrum of AdvSM have not been well characterized.1) To describe the distribution of organ damage in AdvSM patients (pts) at initial presentation or at the time of trial enrollment; 2) To evaluate clinicopathologic and molecular correlates of organ damage.Observational study of adults with AdvSM.Tertiary referral center.Our cohort included 240 AdvSM pts: 66 from the Stanford MPN registry and 174 from the phase I EXPLORER and phase II PATHFINDER studies of avapritinib in AdvSM.None.Hematologic and non-hematologic organ damage as defined by WHO, IWG, and mIWG criteria.Thirty-seven pts (15%) had ASM, 165 (69%) had SM-AHN, and 38 (16%) had MCL. Pts with MCL had the highest transfusion requirement and the largest liver and spleen volumes by imaging. In multivariate analyses comparing SM-AHN to ASM/MCL, SM-AHN pts had higher absolute neutrophil and monocyte counts and presence of SRSF2, ASXL1, or RUNX1 (S/A/R) mutations. ASM/MCL pts had higher tryptase levels and bone marrow mast cell burden. Compared to midostaurin-naïve pts, those who had received midostaurin had a greater bone marrow mast cell burden (P=0.06) but less frequently met WHO liver (P0.001) and WHO malabsorption (P0.001) criteria. Compared to pts with KIT D816V only, pts with ≥1 S/A/R mutations had lower median hemoglobin (P=0.02) and platelet count (P=0.02) and higher direct bilirubin (P=0.02), alkaline phosphatase (P=0.03), and spleen volume (P=0.06). They exhibited more WHO-defined cytopenias (P=0.007) and were more likely to meet WHO hypersplenism criteria (P=0.03).In AdvSM, patterns of organ damage reflect disease subtype, prior therapy, and mutation profile. These data can help inform enrollment of AdvSM pts into clinical trials that currently require ≥1 organ damage findings. Grant Acknowledgments: ASH HONORS Award, NIH grant P30CA124435.

Tissue damage, epithelial alterations, and intraepithelial presence of mast cells (MCs) are characteristics of asthma pathogenesis. Increased alveolar infiltration of MC populations has also been identified as a feature of asthma and other chronic respiratory diseases. The asthma associated receptor, urokinase plasminogen activator receptor (uPAR), has been shown to regulate bronchial epithelial repair responses. However, the impact of MC tryptase and chymase on functional properties and expression of uPAR in alveolar epithelial cells have not been fully investigated. Alveolar epithelial cell migration and wound healing were investigated using holographic live cell imaging of A549 cells in a wound scratch model post stimulation with tryptase or chymase. The expression of uPAR was investigated on the protein and gene level from cellular supernatants and in bronchoalveolar lavage fluid fractions from allergic asthmatics. We found that tryptase improved wound healing capacity, cellular migration and membrane bound uPAR expression. Chymase reduced gap closure capacity, cellular migration and membrane bound uPAR expression but increased soluble uPAR release. Our data suggest a dual regulatory response from the MC proteases in events related to uPAR expression and wound healing which could be important features in asthmatic disease.

This is a “Letter to the Editor” with no abstract.

Degeneration of motor neurons, glial cell reactivity, and vascular alterations in the CNS are important neuropathological features of amyotrophic lateral sclerosis (ALS). Immune cells trafficking from the blood also infiltrate the affected CNS parenchyma and contribute to neuroinflammation. Mast cells (MCs) are hematopoietic-derived immune cells whose precursors differentiate upon migration into tissues. Upon activation, MCs undergo degranulation with the ability to increase vascular permeability, orchestrate neuroinflammation and modulate the neuroimmune response. However, the prevalence, pathological significance, and pharmacology of MCs in the CNS of ALS patients remain largely unknown. In autopsy ALS spinal cords, we identified for the first time that MCs express c-Kit together with chymase, tryptase, and Cox-2 and display granular or degranulating morphology, as compared with scarce MCs in control cords. In ALS, MCs were mainly found in the niche between spinal motor neuron somas and nearby microvascular elements, and they displayed remarkable pathological abnormalities. Similarly, MCs accumulated in the motor neuron-vascular niche of ALS murine models, in the vicinity of astrocytes and motor neurons expressing the c-Kit ligand stem cell factor (SCF), suggesting an SCF/c-Kit-dependent mechanism of MC differentiation from precursors. Mechanistically, we provide evidence that fully differentiated MCs in cell cultures can be generated from the murine ALS spinal cord tissue, further supporting the presence of c-Kit+ MC precursors. Moreover, intravenous administration of bone marrow-derived c-Kit+ MC precursors infiltrated the spinal cord in ALS mice but not in controls, consistent with aberrant trafficking through a defective microvasculature. Pharmacological inhibition of c-Kit with masitinib in ALS mice reduced the MC number and the influx of MC precursors from the periphery. Our results suggest a previously unknown pathogenic mechanism triggered by MCs in the ALS motor neuron-vascular niche that might be targeted pharmacologically. Supplementary Information The online version contains supplementary material available at 10.1186/s40478-021-01241-3.

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 D (1.2 3 baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, upto-date knowledge of hereditary alpha-tryptasemia as a frequent cause of baseline tryptase of 7 mg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cellerelated disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists. (C) 2021 American Academy of Allergy, Asthma & Immunology

Hereditary alpha-tryptasemia (HαT) is an autosomal dominant genetic trait found in 4% to 6% of the general population and defined by excess copies of alpha-tryptase at TPSAB1. Elevated basal serum tryptase (sBT >8 ng/mL) is a defining feature of HαT and appears to result from increased pro-alpha-tryptase synthesis and secretion rather than mast cell activation. It is estimated that approximately one-third of individuals with HαT have associated symptoms, including cutaneous, gastrointestinal, atopic, musculoskeletal, autonomic, and neuropsychiatric manifestations. HαT is found at a disproportionately high rate in systemic mastocytosis and idiopathic anaphylaxis, and is a modifying factor that independently increases the incidence and severity of anaphylaxis. The varied phenotypes associated with HαT may, in part, result from coinheritance of other genetic variants, increased expression of α-/s-tryptase heterotetramers, and/or overexpression of pro-alpha-tryptase, although further studies are needed. There is an accurate diagnostic test available to confirm HαT in patients that can be used in combination with sBT to help risk-stratify individuals in whom bone marrow biopsy is being considered. There is no specific treatment for symptoms associated with HαT, and management is focused on controlling clinical manifestations with mast cell mediator antagonists, aspirin, inhalers, epinephrine, omalizumab, and involvement of other specialists.

Background Mast cells (MCs) are known to contribute to both acute and chronic inflammation. Bronchial epithelial cells are the first line of defence against pathogens and a deficient anti-viral response has been suggested to play a role in the pathogenesis of asthma exacerbations. However, effects of MC mediators on bronchial epithelial immune response have been less studied. The aim of this study is to investigate the direct effects of stimulation with MC proteases, tryptase and chymase, on inflammatory and anti-viral responses in human bronchial epithelial cells (HBECs). Method Cultured BEAS-2b cells and primary HBECs from 3 asthmatic patients were stimulated with tryptase or chymase (0.1 to 0.5 μg/ml) for 1, 3, 6 and 24 h. To study the effects of MC mediators on the anti-viral response, cells were stimulated with 10 μg/ml of viral mimic Poly (I:C) for 3 and 24 h following pre-treatment with 0.5 μg/ml tryptase or chymase for 3 h. Samples were analysed for changes in pro-inflammatory and anti-viral mediators and receptors using RT-qPCR, western blot and Luminex. Results Tryptase and chymase induced release of the alarmin ATP and pro-inflammatory mediators IL-8, IL-6, IL-22 and MCP-1 from HBECs. Moreover, tryptase and chymase decreased the expression of E-cadherin and zonula occludens-1 expression from HBECs. Pre-treatment of HBECs with tryptase and chymase further increased Poly (I:C) induced IL-8 release at 3 h. Furthermore, tryptase significantly reduced type-I and III interferons (IFNs) and pattern recognition receptor (PRR) expression in HBECs. Tryptase impaired Poly (I:C) induced IFN and PRR expression which was restored by treatment of a serine protease inhibitor. Similar effects of tryptase on inflammation and anti-viral responses were also confirmed in primary HBECs from asthmatic patients. Conclusion MC localization within the epithelium and the release of their proteases may play a critical role in asthma pathology by provoking pro-inflammatory and alarmin responses and downregulating IFNs. Furthermore, MC proteases induce downregulation of epithelial junction proteins which may lead to barrier dysfunction. In summary, our data suggests that mast cells may contribute towards impaired anti-viral epithelial responses during asthma exacerbations mediated by the protease activity of tryptase.

Mosquito bites are endured by most populations worldwide. Reactions to mosquito bites range from localized wheals and papules with associated pruritus to rare systemic reactions and anaphylaxis in certain populations. The mechanism of itch is due to introduction of mosquito saliva components into the cutaneous tissue, although the exact pathophysiology is unclear. Histamine is thought to be a key player through mosquito saliva itself or through activation of mast cells by IgE or through an IgE-independent pathway. However, other salivary proteins such as tryptase and leukotrienes may induce non-histaminergic itch. Some individuals have a genetic predisposition for mosquito bites, and people with hematologic cancers, HIV, and other conditions are susceptible to robust reactions. Prevention of mosquito bites is key with physical barriers or chemical repellents. Treatment consists of second-generation antihistamines and topical corticosteroids. Further research on topical treatments that target neural-mediated itch is needed.

IntroductionIn mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, itch is a frequent clinical symptom. Whether mast cells (MCs), eosinophils (Eos) or their mediators play a role in MF-associated itch or disease severity is controversially discussed. Here, we explored the role of MC and Eo numbers in the skin as well as blood levels of their mediators in disease severity and itch.MethodsIn 10 patients with MF and 10 matched control subjects we assessed disease severity, itch, and quality of life impairment using dedicated tools such as the mSWAT, ItchyQoL and DLQI. We analyzed skin biopsies and measured serum levels of tryptase, a mast cell mediator, as well as of the eosinophil products eosinophil cationic protein (ECP) and major basic protein (MBP).ResultsThe presence of chronic itch, in four of 10 patients, was associated with significantly higher disease severity (mSwat), larger body surface area affected, and stronger QoL impairment (Itchy-Qol, DLQI). Serum levels of tryptase, but not ECP and MBP, were linked with patient-reported disease severity, body surface area affected, and the presence of itch. Three of the four patients with chronic itch, but none of the six patients without, had tryptase levels above >6µg/l. Numbers of MCs in the papillary dermis were higher in MF skin lesions then in non-lesional skin of MF patients and skin of healthy controls.DiscussionThe MC-mediator tryptase, in MF, is linked to disease activity and impact, most prominently to itch. Our findings call for larger studies that explore the role of MCs, tryptase and other MC mediators as drivers of itch and their role in MF pathogenesis.

To discuss our evolving knowledge about the genetic variations in human tryptase and recent advances in associated clinical phenotypes.Hereditary alpha-tryptasemia (HAT) is an autosomal dominant genetic trait and a common cause of elevated basal serum tryptase (BST) in Western populations. It is a risk factor for severe anaphylaxis and an established modifier of mast cell mediator-associated symptoms among patients with systemic mastocytosis (SM).The unique properties of naturally occurring alpha/beta-tryptase heterotetramers may explain certain elements of phenotypes associated with HAT. Understanding the physiology of tryptases and how this may relate to the clinical features associated with HAT is the first step in identifying optimal medical management and targets for novel therapeutics.

Evaluation of perioperative hypersensitivity (POH) is challenging, and accurate screening tools are needed to optimize the diagnostic process. We aimed to assess and validate the diagnostic value of a published algorithm (using tryptase and clinical presentation) to identify appropriate individuals for further testing for IgE-mediated POH.We analysed the clinical presentation (tryptase elevation, cardiovascular, respiratory, skin involvement) of patients proceeding to testing for possible IgE-mediated POH at a single tertiary referral centre, relative to subsequent skin testing and specific IgE results. Clinical presentations by drug class were also determined.In 293 consecutive patients, the use of a published algorithm based on one or more of; (i) defined increase in serum tryptase, (ii) involvement of at least two-organ systems, or (iii) presentation with new urticaria and/or angioedema; was highly sensitive [98.8% (CI95: 95.7-99.9%)] but less specific [34.6% (CI95: 25.7-44.4%)] in identifying patients testing positive on skin testing and/or specific IgE. Presentation with cardiovascular symptoms was also sensitive [89.8%(CI95: 84.2-94.0%)], while the combination of respiratory symptoms and increased tryptase was most specific [85.9%(CI95:76.6-92.5%)]. Respiratory involvement was more common in neuromuscular blocking agent allergy, while urticaria/angioedema was more common in antibiotic allergy.The published algorithm (of tryptase rise, two-organ involvement or new urticaria/angioedema) is highly sensitive, and appropriate as a screening tool to identify patients suitable for testing for IgE-mediated POH.

Mast cells (MCs) produce a variety of mediators, including proteases—tryptase, chymase, and carboxypeptidases—which are important for the immune response. However, a detailed assessment of the mechanisms of biogenesis and excretion of proteases in melanoma has yet to be carried out. In this study, we present data on phenotype and secretory pathways of proteases in MCs in the course of melanoma. The development of melanoma was found to be accompanied by the appearance in the tumor-associated MC population of several pools with a predominant content of one or two specific proteases with a low content or complete absence of others. Elucidation of the molecular and morphological features of the expression of MC proteases in melanoma allows us a fresh perspective of the pathogenesis of the disease, and can be used to clarify MCs classification, the disease prognosis, and evaluate the effectiveness of ongoing antitumor therapy.

Mast cells in the osteoarthritis (OA) synovium correlate with disease severity. This study aimed to further elucidate the role of mast cells in OA by RNA-Seq analysis and pharmacological blockade of the activity of histamine, a key mast cell mediator, in murine OA.We examined OA synovial tissues and fluids by flow cytometry, immunostaining, single-cell and bulk RNA-Seq, qPCR, and ELISA. Cetirizine, a histamine H1 receptor (HFlow cytometry and immunohistology analysis of OA synovial cells revealed KITBased on differential expression of prototypical and distinct mast cell markers, human OA joints can be stratified into mast cell-high, -medium, and -low synovial tissue pathotypes. Pharmacologic blockade of histamine activity holds the potential to improve OA disease outcome.

Introduction: This study aimed to evaluate the preliminary diagnosis, demographic characteristics, and outcomes of patients whose serum total tryptase levels were measured while in a tertiary pediatric hospital and to ascertain the role of serum tryptase levels in the etiology, diagnosis, severity, and course of systemic anaphylaxis. Methods: Patients ages between 1 month and 17 years who were followed up in the pediatric emergency department or as inpatients and with a diagnosis of immediate-type reactions between September 1, 2019, and August 31, 2021, were included in the study. Patient data were obtained retrospectively by examination of medical records and patient observation forms. Results: It was determined that serum tryptase levels were measured in a total of 310 patients during the study period. One hundred and fifty-five patients who met the defined diagnostic criteria were named as the anaphylaxis group and their data were detailed. The serum tryptase elevation was detected in 15.5% of the patients among the samples that met the anaphylaxis diagnostic criteria. No relationship was found between the serum total tryptase levels, the triggering factor, and the severity of anaphylaxis. Discussion: Anaphylaxis is a complex syndrome that involves different phenotypes that develop with various triggers in which different immunologic pathways, cell types, and mediators play a role. Serial measurements, including the basal value measured at least 24 hours after the symptoms disappear, are useful to confirm the diagnosis and guide the diagnostic tests during the follow-up, especially allergy evaluation.

BackgroundThe systemic inflammatory response post-SARS-CoV-2 infection increases pro-inflammatory cytokine production, multi-organ damage, and mortality rates. Mast cells (MC) modulate thrombo-inflammatory disease progression (e.g., deep vein thrombosis) and the inflammatory response post-infection.ObjectiveTo enhance our understanding of the contribution of MC and their proteases in SARS-CoV-2 infection and the pathogenesis of the disease, which might help to identify novel therapeutic targets.MethodsMC proteases chymase (CMA1), carboxypeptidase A3 (CPA3), and tryptase beta 2 (TPSB2), as well as cytokine levels, were measured in the serum of 60 patients with SARS-CoV-2 infection (30 moderate and 30 severe; severity of the disease assessed by chest CT) and 17 healthy controls by ELISA. MC number and degranulation were quantified by immunofluorescent staining for tryptase in lung autopsies of patients deceased from either SARS-CoV-2 infection or unrelated reasons (control). Immortalized human FcεR1+c-Kit+ LUVA MC were infected with SARS-CoV-2, or treated with its viral proteins, to assess direct MC activation by flow cytometry.ResultsThe levels of all three proteases were increased in the serum of patients with COVID-19, and strongly correlated with clinical severity. The density of degranulated MC in COVID-19 lung autopsies was increased compared to control lungs. The total number of released granules and the number of granules per each MC were elevated and positively correlated with von Willebrand factor levels in the lung. SARS-CoV-2 or its viral proteins spike and nucleocapsid did not induce activation or degranulation of LUVA MC in vitro.ConclusionIn this study, we demonstrate that SARS-CoV-2 is strongly associated with activation of MC, which likely occurs indirectly, driven by the inflammatory response. The results suggest that plasma MC protease levels could predict the disease course, and that severe COVID-19 patients might benefit from including MC-stabilizing drugs in the treatment scheme.

Mast cells (MCs) are critically involved in microbial defense by releasing antimicrobial peptides (such as cathelicidin LL-37 and defensins) and phagocytosis of microbes. In past years, it has become evident that in addition MCs may eliminate invading pathogens by ejection of web-like structures of DNA strands embedded with proteins known together as extracellular traps (ETs). Upon stimulation of resting MCs with various microorganisms, their products (including superantigens and toxins), or synthetic chemicals, MCs become activated and enter into a multistage process that includes disintegration of the nuclear membrane, release of chromatin into the cytoplasm, adhesion of cytoplasmic granules on the emerging DNA web, and ejection of the complex into the extracellular space. This so-called ETosis is often associated with cell death of the producing MC, and the type of stimulus potentially determines the ratio of surviving vs. killed MCs. Comparison of different microorganisms with specific elimination characteristics such as S pyogenes (eliminated by MCs only through extracellular mechanisms), S aureus (removed by phagocytosis), fungi, and parasites has revealed important aspects of MC extracellular trap (MCET) biology. Molecular studies identified that the formation of MCET depends on NADPH oxidase-generated reactive oxygen species (ROS). In this review, we summarize the present state-of-the-art on the biological relevance of MCETosis, and its underlying molecular and cellular mechanisms. We also provide an overview over the techniques used to study the structure and function of MCETs, including electron microscopy and fluorescence microscopy using specific monoclonal antibodies (mAbs) to detect MCET-associated proteins such as tryptase and histones, and cell-impermeant DNA dyes for labeling of extracellular DNA. Comparing the type and biofunction of further MCET decorating proteins with ETs produced by other immune cells may help provide a better insight into MCET biology in the pathogenesis of autoimmune and inflammatory disorders as well as microbial defense.

Tuberculosis (TB) is still a major worldwide health threat and primarily a lung disease. The innate immune response against Mycobacterium tuberculosis (Mtb) is orchestrated by dendritic cells, macrophages, neutrophils, natural killer cells and apparently mast cells (MCs). MCs are located at mucosal sites including the lungs and contribute in host-defence against pathogens, but little is known about their role during Mtb infection. This study investigates the location and characteristics of MCs in TB lesions to assess their contribution to TB pathology. To this purpose, number, location and phenotype of MCs was studied in 11 necropsies of pulmonary TB and 3 necropsies of non-TB infected lungs that were used as controls. MCs were localised at pneumonic areas, in the granuloma periphery and particularly abundant in fibrotic tissue. Furthermore, MCs displayed intracellular Mtb and IL-17A and TGF-β immunostaining. These findings were validated by analysing, post-mortem lung tissue microarrays from 44 individuals with pulmonary TB and 25 control subjects. In affected lungs, increased numbers of MCs expressing intracellularly both tryptase and chymase were found at fibrotic sites. Altogether, our data suggest that MCs are recruited at the inflammatory site and that actively produce immune mediators such as proteases and TGF-β that may be contributing to late fibrosis in TB lesions.

Suicidal ingestion of food which the victim is aware they are allergic to is an exceptional occurrence in the forensic field. To the best of our knowledge, no cases of suicidal food anaphylaxis have been reported to date. Therefore we present the first case described in the literature. A 30-year-old prisoner was found dead inside his cell with the remains of a peach remains next to his body, and a handwritten farewell note in his pocket. The autopsy revealed only non-specific findings, while laboratory investigations (serological, toxicological, histological, and immunohistochemical) played a pivotal role in determing the cause and manner of death. In particular, a high titer of both total and specific IgE antibodies was detected, as well as an increase of the tryptase level in cadaveric blood. Moreover, a massive concentration of salicylates was measured in the gastric contents. Microscopically, cellular residues characterized by a vegetal structure were observed in the gastric contents and elements suggestive of mast cells were detected in the glottis, lungs, and myocardium. The immunohistochemical investigation with anti-CD117 and anti-tryptase antibodies showed positivity for mast cells, some of which appeared degranulated. Such findings were entirely consistent with an acute systemic anaphylactic reaction triggered by allergy. Therefore, the prisoner’s death was attributed to self-induced food anaphylaxis caused by the ingestion of peaches. This conclusion was achieved based only on circumstantial data, anamnestic information, autopsy findings, and multiple laboratory results. This integrated approach should be used to pursue a post-mortem diagnosis of anaphylaxis.

Background: Many patients report questionable drug hypersensitivity reactions (DHR) to betalactam antibiotics. A workup is required for objectivation. Direct drug provocation tests (DPTs) omitting a prior allergy workup are increasingly recommended as the primary diagnostic approach. However, apart from the risk of severe side effects, DPTs often are a scarce resource in overloaded healthcare-systems. We investigated how many cases can be solved by drug-specific history, drug-specific IgE, and skin tests obviating the need for DPT. Methods: We conducted a chart review in a retrospective cohort of 932 patients in an allergy outpatient centre from 2016 to 2017. Patients had been submitted to drug-specific history and specific IgE-, skin prick-, intradermal- and patch-tests with early and late readings with a series of penicillins and cephalosporins but DPTs were no option. Results: Overall, positive in vitro and/or skin tests were found in 96/932 (10.3%) patients. Drug-specific IgE was detected in 40/932 (4.3%) patients, 61/787 (7.8%) patients had positive skin tests. In vitro tests to Pencillin V showed the highest rate of positivity 24/479 (5.0%) and early readings of ampicillin the highest amongst the skin tests (3/49, 6.1%). Immediate skin tests were more often positive than delayed ones (75:45). The combination of all parameters including drug-specific history solved 346/932 (37.1%) cases while 586/932 (62.9%) remained unresolved. Self-reported DHR could be less often confirmed in females and young children (p