IgE and IgG4 Repertoire in Asymptomatic HDM-Sensitized and HDM-Induced Allergic Rhinitis Patients

Introduction: Asymptomatic sensitization is defined as the presence of positive skin prick test (SPT) and/or positive serum allergen-specific IgE in the absence of clinical allergic symptoms. Currently, there is no convincing explanation why some people with positive allergen tests do not show symptoms. We aimed to investigate the house dust mite (HDM)-specific IgE and IgG4 repertoire in asymptomatic HDM-sensitized subjects and HDM-induced allergic rhinitis (AR) patients. Methods: A total of 48 subjects sensitized to HDM were included in this study: 27 had AR with/without asthma (symptomatic group), and 21 had no allergic symptoms (asymptomatic group). Six healthy individuals served as control group. Peripheral blood samples were collected for serum IgE and IgG4 assay and basophil activation tests (BATs). IgE and IgG4 assay included antibodies to Dermatophagoides (Der) p1, 2, 7, 10, 21, 23, and Der f1, 2. Results: AR patients had a larger wheal diameter of SPT (7.0 vs. 3.0 mm, p < 0.0001) and a higher specific IgE to Der p (15.50 vs. 0.70 KU/L, p < 0.0001) than asymptomatic subjects. They also showed more frequent sensitization to Der p1 and Der p2 (both p < 0.05). However, the total IgE and specific IgG4 did not differ significantly between the 2 groups. The basophil activation response after being stimulated with HDM was observed to be higher in AR patients (all p < 0.05). Conclusions: There are differences in SPT, serum-specific IgE to Der p, component allergen Der p1 and Der p2 level and BAT between AR patients and asymptomatic subjects sensitized to HDM. IgG4 alone cannot differentiate asymptomatic individuals from AR patients.