Dermatitis herpetiformis: relation between circulating immune complexes, small-intestinal mucosal status, and immunohistopathological findings.

Some aspects of humoral immunity and the status of the jejunal mucosa were investigated in 22 patients with classical dermatitis herpetiformis (DH). The mucosal status was characterized on the basis of immuno- and histopathological findings and functional analysis of malabsorption and disaccharidase activity. There was no significant abnormality in the serum immunoglobulins, whereas the IgA and C3 contents of the circulating immune complexes (established by polyethylene glycol precipitation and inverse radial immunodiffusion techniques) were significantly elevated. Polyorgan-specific autoantibodies of IgG type were present in the sera of 95% of the 22 patients. Functional analysis of the gastrointestinal tract revealed some abnormality in all of the 18 cases examined, while direct immunofluorescence studies demonstrated an increased number of subepithelial IgA lymphoid cells in all of the 15 cases examined. These findings did not correlate well with the jejunal mucosal morphology. This study supports the view that IgA deposited in the skin is formed in the gut.