Immunoglobulin a dermatoses

Abstract

Immunoglobulin A (IgA) dermatoses represent a distinct but diverse category of immunologic skin diseases, including linear IgA bullous dermatosis, dermatitis herpetiformis, IgA subcorneal pemphigus, IgA intraepidermal pemphigus and IgA vasculitis (Henoch-Schönlein purpura). The common findings that tie all of these disorders together are the cutaneous deposition of IgA at the histopathologic site of inflammation on direct immunofluorescence microscopy and a neutrophilic inflammatory infiltrate on hematoxylin and eosin staining of involved skin. IgA is found in respiratory, gastrointestinal and genitourinary mucosal secretions, as well as human serum. The IgA dermatoses share activation of the IgA receptor, FcaR1, on neutrophils, which is also present on eosinophils and monocytes. This receptor activation starts an inflammatory cascade believed to be essential in these disorders that include: a neutrophilic response, endocytosis, antibody-dependent cell-mediated cytotoxicity, the respiratory burst, degranulation in the skin and subsequent tissue damage. The main therapy for these disorders remains dapsone, a sulfone antibiotic, and its related medications, which are effective agents against neutrophil activity that include inhibition of adhesion, chemotaxis and myeloperoxidase production for the respiratory burst. Topical therapy consists mainly of high potency corticosteroids.