Circulating antibodies to gliadin subfractions in dermatitis herpetiformis and linear IgA dermatoses

Abstract

Dermatitis herpetiformis (DH) and coeliac disease are associated and the rash of DH is gluten-dependent. The gliadin fraction responsible for the rash is unknown. In linear IgA dermatoses the role of gluten in the skin eruption remains controversial. Anti-gliadin antibodies (AGA) were measured by an enzyme-linked immunosorbent assay in 10 normal controls; 35 patients with dermatitis herpetiformis (DH); 14 adults with linear IgA disease; and 13 patients with chronic bullous dermatosis of childhood. The presence of enteropathy was assessed by jejunal biopsy and intra-epithelial lymphocyte (IEL) counts. DH with normal IEL counts on normal diet: IgG and IgA-AGA identical to controls. DH with raised IEL counts on gluten-free diet: slightly elevated IgG and IgA-AGA. DH with raised IEL counts on a normal diet: IgG and IgA were higher, with median IgG 1:2048 (control 1:512) median IgA 1:512 (control 1:128). DH patients with high IgG AGA had elevated titres to α, β, γ, and ω subfractions. The highest levels were for α and the lowest for ω. For linear IgA disease IgG is normal but adults had raised IgA-AGA compared to controls (P= 0.005). In dermatitis herpetiformis the presence of anti-gliadin antibody was dependent on the degree of enteropathy, and, if present, was directed against all gliadin subfractions. The significance of the elevated IgA—AGA in the linear IgA disease is unknown.