Basophils from allergic patients are neither hyperresponsive to activation signals nor hyporesponsive to inhibition signals.

BACKGROUND: Basophil activation contributes to inflammatory reactions, especially in allergy. It is controlled, both positively and negatively, by several mechanisms. High-affinity IgE receptors (FcεRI) generate a mixture of activation and inhibition signals when aggregated, the ratio of which depends on the concentration of allergen recognized by receptor-bound IgE. Low-affinity IgG receptors (FcγRIIA/B) generate inhibition signals when coengaged with FcεRI by allergen-antibody immune complexes. Commensal and probiotic bacteria, such as Lactobacillus paracasei, generate inhibition signals through still unclear mechanisms. OBJECTIVE: We sought to investigate whether mechanisms that control, both positively and negatively, basophil activation, which were unraveled and studied in basophils from healthy donors, are functional in allergic patients. METHODS: FcεRI and FcγRIIA/B expression, FcεRI-dependent activation, FcεRI-dependent inhibition, and FcγRIIB-dependent inhibition were examined in blood basophils incubated overnight with or without L paracasei and challenged under 10 experimental conditions. Basophils from healthy donors were compared with basophils from patients who consulted an allergology outpatient clinic over a period of 3 months with respiratory allergy, anaphylaxis antecedents, chronic urticaria, and/or atopic dermatitis. RESULTS: Patients' basophils expressed neither more FcεRI nor less FcγRIIB than basophils from healthy donors. They were neither hyperreactive to positive regulation nor hyporeactive to negative regulation, irrespective of the receptors or mechanisms involved and the allergic manifestations of the patients. CONCLUSION: Regulatory mechanisms that control basophil activation are fully functional in allergic patients. Intrinsic defects in these mechanisms do not explain allergic manifestations. Based on these mechanisms, immune checkpoint modifiers can be developed as novel therapeutic tools for allergy.

Opiorphin levels in fluids of burning mouth syndrome patients: a case-control study.

OBJECTIVES: Idiopathic Burning mouth syndrome (iBMS) is a poorly understood affection characterized by persistent pain in the oral cavity without any clinical or biological abnormality. Opiorphin is a natural inhibitor of enkephalin-inactivating ectopeptidases, mainly produced by salivary glands, that has demonstrated analgesic properties. The objective of the present case-control study was to test the hypothesis of a decrease in opiorphin levels in iBMS patients. MATERIALS AND METHODS: Twenty-one iBMS patients and 21 matched controls subjects were included between 2011 and 2013. Submandibular and sublingual salivary, blood, and urinary opiorphin levels of iBMS patients were compared to controls. RESULTS: Results are expressed as mean values ± SD and compared using the Wilcoxon Signed Rank test. Correlations were analyzed with Spearman coefficient. The level of significance was fixed at p < 0.05. Opiorphin levels in iBMS and controls were respectively (in ng/ml) in basal saliva: 37.8 ± 42.5 and 67.6 ± 188.9 (p = NS); stimulated saliva: 28.8 ± 25.3 and 31.1 ± 29.1 (p = NS); blood: 4.6 ± 5.4 and 1.9 ± 1.4 (p < 0.05); and urines: 68.5 ± 259.8 and 8.9 ± 6.2 (p = NS). CLINICAL RELEVANCE: In conclusion, the lack of significative difference in salivary opiorphin levels between iBMS and controls does not favor a direct local role for opiorphin in the etiopathogeny of iBMS. However, higher blood opiorphin levels may reflect a systemic dysregulation in iBMS. Trial registration NCT02686359 https://clinicaltrials.gov/ct2/show/NCT02686359.

Human basophils express the glycosylphosphatidylinositol-anchored low-affinity IgG receptor FcgammaRIIIB (CD16B).

Basophils express not only high-affinity IgE receptors, but also low-affinity IgG receptors. Which, among these receptors, are expressed by human basophils is poorly known. Low-affinity IgG receptors comprise CD32 (FcgammaRIIA, FcgammaRIIB, and FcgammaRIIC) and CD16 (FcgammaRIIIA and FcgammaRIIIB). FcgammaRIIA, FcgammaRIIC, and FcgammaRIIIA are activating receptors, FcgammaRIIB are inhibitory receptors, FcgammaRIIIB are GPI-anchored receptors whose function is poorly understood. Basophils were reported to express FcgammaRII, but not FcgammaRIII. We aimed at further identifying basophil IgG receptors. Basophils from normal donors and from patients suffering from an allergic skin disease (atopic dermatitis), allergic respiratory diseases (allergic rhinitis and asthma), or a nonallergic skin disease (chronic urticaria) were examined. We found that normal basophils contain FcgammaRIII transcripts and express FcgammaRIIIB, but not FcgammaRIIIA, which were detected on 24-81% basophils from normal donors and on 12-100% basophils from patients. Noticeably, the proportion of FcgammaRIIIB(+) basophils was significantly lower in atopic dermatitis patients than in other subjects. This decreased FcgammaRIII expression was not correlated with an activated phenotype of basophils in atopic dermatitis patients, although FcgammaRIIIB expression was down-regulated upon basophil activation by anti-IgE. Our results challenge the two dogmas 1) that basophils do not express FcgammaRIII and 2) that FcgammaRIIIB is exclusively expressed by neutrophils. They suggest that a proportion of basophils may be lost during enrichment procedures in which FcgammaRIII(+) cells are discarded by negative sorting using anti-CD16 Abs. They unravel an unexpected complexity of IgG receptors susceptible to modulate basophil activation. They identify a novel systemic alteration in atopic dermatitis.

A three-year-analysis of fixed drug eruptions in hospital settings in France.

Fixed drug eruption (FDE) is one of the most typical cutaneous drug adverse reactions. This localized drug-induced reaction is characterized by its relapse at the same sites. Few large series of FDE are reported. The aim of this study was to retrospectively collect and analyse well informed cases observed in a hospital setting. This study involved 17 academic clinical centers. A French nation-wide retrospective multicentric study was carried out on a 3-year-period from 2005 to 2007 by collecting data in seventeen departments of dermatology in France. Diagnosis of FDE was based essentially on clinical findings, at times confirmed by pathological data and patch-testing. Records were reviewed for demographics, causative drugs, localization, severity, and patch-tests, when available. Fifty nine cases were analysed. Patients were 59-years-old on average, with a female predilection. The most common drug was paracetamol, followed by the non-steroidal anti inflammatory drugs. The time between drug intake and skin symptoms was, on average, two days. Beside these classical characteristics, some original findings were found including, a frequent non pigmentation course and a sex-dependent pattern of distribution. Women often had lesions on the hands and feet, and men on the genitalia. Given the fact that skin pigmentation is an inconstant feature of FDE, its French name (erythème pigmenté fixe) should be reconsidered. The sex-dependent distribution could help our understanding of the pathophysiology of fixed drug eruption.

An IgG-induced neutrophil activation pathway contributes to human drug-induced anaphylaxis.

Anaphylaxis is a systemic acute hypersensitivity reaction that is considered to depend on allergen-specific immunoglobulin E (IgE) antibodies and histamine release by mast cells and basophils. Nevertheless, allergen-specific IgG antibodies have been proposed to contribute when the allergen is an abundant circulating large molecule, e.g., after infusions of therapeutic antibodies or dextran. Data from animal models demonstrate a pathway involving platelet-activating factor (PAF) release by monocytes/macrophages and neutrophils activated via their Fc gamma receptors (FcγRs). We hypothesized that such a pathway may also apply to small drugs and could be responsible for non-IgE-mediated anaphylaxis and influence anaphylaxis severity in humans. We prospectively conducted a multicentric study of 86 patients with suspected anaphylaxis to neuromuscular-blocking agents (NMBAs) during general anesthesia and 86 matched controls. We found that concentrations of anti-NMBA IgG and markers of FcγR activation, PAF release, and neutrophil activation correlated with anaphylaxis severity. Neutrophils underwent degranulation and NETosis early after anaphylaxis onset, and plasma-purified anti-NMBA IgG triggered neutrophil activation ex vivo in the presence of NMBA. Neutrophil activation could also be observed in patients lacking evidence of classical IgE-dependent anaphylaxis. This study supports the existence of an IgG-neutrophil pathway in human NMBA-induced anaphylaxis, which may aggravate anaphylaxis in combination with the IgE pathway or underlie anaphylaxis in the absence of specific IgE. These results reconcile clinical and experimental data on the role of antibody classes in anaphylaxis and could inform diagnostic approaches to NMBA-induced acute hypersensitivity reactions.

Prevalence of monoclonal gammopathy in patients presenting with acquired angioedema type 2.

PURPOSE: Acquired angioedema type 1 is characterized by a C1 inhibitor deficiency in patients with lymphoproliferative disorders, whereas acquired angioedema type 2 is characterized by anti-C1 inhibitor antibodies, and has not been thought to be associated with lymphoproliferative disease. We studied the clinical features, complement profiles, and associated diseases in 19 new patients with diagnosed acquired angioedema type 2. SUBJECTS AND METHODS: Plasma concentrations and functional activity of complement components were measured by conventional techniques. Functional C1 inhibitor activity was assessed by a chromogenic assay. Autoantibodies to C1 inhibitor were detected using an enzyme-linked immunosorbent assay. RESULTS: The 11 men and 8 women (median age, 60 years) presented with recurrent attacks of angioedema. All patients had detectable anti-C1 inhibitor antibodies in serum. A monoclonal gammopathy was detected in 12 patients (63%) at the time of diagnosis, 11 of whom had an immunoglobulin peak of the same heavy- and light-chain isotypes as the acquired anti-C1 inhibitor antibody. Three of these 12 patients developed a malignant lymphoproliferative disease. CONCLUSION: As with type 1 disease, a large proportion of patients with acquired angioedema type 2 have a lymphoproliferative disorder.