Detection of circulating IgG autoantibody to FcεRIα in sera from chronic spontaneous urticaria patients

Abstract Backgrounds Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by itchy wheals of at least 6 weeks in duration, wherein the autoimmune mechanism is involved to activate IgE receptors (FceRIα) on mast cells. We aimed to assess levels of IgG autoantibody against FceRIα in sera from CSU patients using dot-blot immunoassay. Methods We performed a hospital-based cross-sectional study of 125 CSU patients (64 ASST-positive, 61 ASST-negative) and 64 age-and sex-matched healthy controls. The cut-off value of IgG FceRIα autoantibody was determined as the mean intensity plus two standard deviations of values in controls. Positivity for IgG autoantibody to FceRIα was analyzed according to clinical parameters of disease duration, urticaria activity score (UAS), ASST, response to antihistamine treatment, complement levels, and the presence of other autoantibodies. Nonparametric tests were applied for statistical analyses. Results IgG positivity to FceRIα was noted in 24.8% of CSU patients and was significantly more frequent in ASST-positive patients than in ASST-negative patients (32.8% vs 16.4%, P  = 0.040). Only 3.1% of healthy controls had this autoantibody. Complement 3 levels were significantly lower in anti-FceRIα antibody-positive patients than antibody-negative patients (109.8 ± 19.9 vs 123.1 ± 30.9, P  = 0.035). No significant associations were found between IgG positivity to FceRIα and UAS, serum total IgE levels, atopic status, clinical responses to antihistamines, or the presence of anti-thyroid and anti-nuclear antibodies. Conclusion These findings suggest that circulating IgG autoantibody to FceRIα in a subset of patients may be involved in the autoimmune mechanism of CSU. Further studies are needed to clarify its clinical significance.