Anti‐FcεRIα serum autoantibodies in different subtypes of urticaria

Abstract

Background: In recent years, a histamine‐releasing anti‐Fc_εRIα autoantibody has been demonstrated in about one‐third of patients with chronic urticaria. However, its clinical significance is still unclear. The objective was to detect a possible correlation between the occurrence of the anti‐Fc_εRIα autoantibody and the clinical type or cause of urticaria. Methods: Sera from 66 consecutively seen in‐ and outpatients with various types of urticaria and five healthy controls were examined for the presence of anti‐Fc_εRIα autoantibodies with a sandwich ELISA technique. In addition, basophil histamine release was studied in 13 autoantibody‐positive sera. Results: Anti‐Fc_εRIα autoantibodies were found in 17/48 patients with chronic urticaria, in 2/4 with angioedema, in 1/2 with urticarial vasculitis, and in 2/11 with dermographic urticaria. However, no anti‐Fc_εRIα autoantibodies were detected in acute, cold, or delayed‐pressure urticaria; in urticaria pigmentosa; or in normal controls. Of all chronic urticaria patients, 22 were classified as idiopathic since no underlying cause could be found. Of this group, seven were seropositive for anti‐Fc_εRIα. However, anti‐Fc_εRIα was also found in patients who went into remission after treatment of identified causes; namely, in one with type I allergy, one with drug intolerance, one with Helicobacter infection, and six with food intolerance. The autoantibody was also detected in 2/4 patients with associated autoimmune diseases. Functional activity was shown in basophil histamine release in 3/4 autoantibody‐positive sera of patients with chronic idiopathic urticaria and in 4/6 autoantibody‐positive sera of patients who went into remission after the treatment of underlying causes. Conclusions: These data confirm that anti‐Fc_εRIα autoantibodies in urticaria are mostly found in chronic urticaria. Furthermore, their detection independently of the apparent cause of the urticaria suggests that as yet unidentified mechanisms must be operative, possibly related to the chronic inflammatory process and/or individual predispositions that favor their induction.