Rheumatoid factor in sera of dermatitis herpetiformis patients.

Serum specimens from 44 patients with dermatitis herpetiformis (DH) and 42 control patients were analyzed with solid-phase radioimmunoassay (RIA) developed to detect IgG and IgM class antibodies against herpes simplex virus (HSV) envelope antigen. They were also tested with different tests to detect rheumatoid factor (RF) as well as serum antibodies to gastric parietal cells, glomerular basement membrane, smooth muscle, mitochondria and nuclei. Total serum IgG, IgM and IgA quantification was performed concurrently. IgM class antibodies reacting in HSV envelope antigen RIA were found in 47.8% of the DH patients, but in none of the controls. The age distribution of the IgM positive patients was in accordance with the appearance of RF, representing elderly persons. The presence of RF in serum specimens was confirmed by removing the IgM reactivity with heat aggregated human gamma globulin adsorption and in 13 patients with positive serological tests for RF. No correlation was found with the appearance of RF and duration or severity of the disease or with the detection of RF and serum total IgM concentration. In DH patients antibodies to gastric parietal cells were found in 6 and to smooth muscle in 1 of 32 specimens tested.