Comparison of immunoglobulin and complement deposition in multiple biopsies from the uninvolved skin in dermatitis herpetiformis.

The distribution of immunoglobulins and C3 component of complement (C3) in the skin of twenty-four patients with dermatitis herpetiformis was studied. Skin biopsies were taken from three sites, the extensor surface of the elbow, the flexor surface of the forearm and from the thigh. Twenty-two (90%) patients showed variation in deposits of immunoglobulins and C3 at the three sites. IgA was present in all patients, but differed in quantities deposited at the three sites in nineteen (80%) patients. Similar variation between sites was observed with IgG, IgM and C3. There was variation within three biopsies, IgA being absent from some sections and present in others. Three patients had a continuous pattern of IgA deposition. One had both continuous and papillary deposits within a single section. There was no difference in the incidence or quantity of immunoglobulin and C3 between the elbow, forearm and thigh. There was observed to be a diminution in quantity of IgA and incidence of C3 in patients taking a gluten-free diet. Deposition of IgA, IgM, IgG and C3 is not uniform throughout the skin and conclusions drawn from the quantity of immunoglobulin and C3 in a single biopsy may not be reliable.