Detection of serum IgG autoantibodies to Fc epsilon RI alpha by ELISA in patients with chronic spontaneous urticaria

Background Mast cells are a key effector cell in the pathogenesis of chronic spontaneous urticaria (CSU) and activated by circulating Fc epsilon RI-specific IgG as well as IgE. This study evaluated the prevalence of circulating autoantibodies to Fc epsilon RI alpha in the sera of CSU patients. Methods Eighty-eight patients with CSU and 76 healthy controls (HCs) were enrolled. To detect circulating autoantibodies (IgG/IgA/IgM) to Fc epsilon RI alpha, ELISA was done using YH35324 (as a solid phase antigen), and its binding specificity was confirmed by the ELISA inhibition test. The antibody levels were presented by the ratio of YH35324-preincubated to mock-preincubated absorbance values. Clinical and autoimmune parameters, including atopy, urticaria activity score (UAS), serum total/free IgE levels, serum antinuclear antibody (ANA) and autologous serum skin test (ASST) results, were assessed. The autoimmune group was defined if CSU patients had positive results to ASST and/or ANA. Results The ratio of serum IgG to Fc epsilon RI alpha was significantly lower in CSU patients than in HCs (P<0.05), while no differences were noted in serum levels of IgG to recombinant Fc epsilon RI alpha or IgA/IgM autoantibodies. The autoimmune CSU group had significantly lower ratios of IgG/IgA (not IgM) autoantibodies to Fc epsilon RI alpha than the nonautoimmune CSU group (P<0.05 for each). No significant associations were found between sex, age, atopy, urticaria duration, UAS, or serum total/free IgE levels according to the presence of IgG/IgA/IgM antibodies. Conclusions This study confirmed the presence of IgG to Fc epsilon RI alpha in the sera of CSU patients, especially those with the autoimmune phenotype.