IgM and IgA in addition to IgG autoantibodies against FcɛRIα are frequent and associated with disease markers of chronic spontaneous urticaria.

Increased serum levels of IgM-anti-FcɛRIα are common in patients with CSU and linked to features of autoimmune CSU. The role and relevance of autoantibodies to FcɛRIα in CSU can and should be further characterized in future studies, and our novel assay can help with this.