Basophil Phenotypes in Chronic Idiopathic Urticaria in Relation to Disease Activity and Autoantibodies

Abstract

Potentially pathogenic IgG autoantibodies to IgE or its receptor, Fc epsilonRIalpha, have been detected in approximately 40% of chronic idiopathic urticaria (CIU) patients. CIU patients' basophils display distinct altered Fc epsilonRIalpha-mediated degranulation. CIU patients with basophil histamine release in response to polyclonal goat anti-human IgE > or = 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-Fc epsilonRIalpha and anti-IgE. IgG anti-Fc epsilonRIalpha 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.