Basophil phenotypes in chronic idiopathic urticaria in relation to disease activity and autoantibodies

Potentially pathogenic IgG autoantibodies to IgE or its receptor, FcεRIα, have been detected in ∼40% of chronic idiopathic urticaria (CIU) patients. CIU patients' basophils display distinct altered FcεRIα-mediated degranulation. CIU patients with basophil histamine release in response to polyclonal goat anti-human IgE ≥10% are classified as CIU responders (CIU-R) and <10% are CIU non-responders (CIU-NR). We compared the presence of autoantibodies to basophil degranulation phenotypes and to disease status (active or inactive). Sera were collected from non-CIU subjects and CIU subjects who participated in a longitudinal study of disease severity and had defined basophil degranulation phenotypes. Immunoenzymetric assays (IEMA) quantified IgG anti-FcεRIα and anti-IgE. IgG anti-FcεRIα antibody was detected in 57% of CIU-R (n = 35), 55% of CIU-NR (n = 29), and 57% of non-CIU subjects (n = 23), whereas IgG anti-IgE was present in 43% of CIU-R, 45% of CIU-NR, and 30% of non-CIU subjects. Both the autoantibody levels and the functional basophil phenotype remained stable in subjects with active disease (n = 16), whereas there was an enhancement in basophil function as subjects evolved into a state of remission (n = 6), which appears independent of the presence of autoantibody. IEMAs detected a similar frequency of autoantibodies in CIU-R, CIU-NR, and non-CIU subjects. Basophil function may be independent of IEMA-detected autoantibodies.