Deposits of immunoglobulins and complement in skin of patients with rheumatoid arthritis. Influence of anti-rheumatic treatment.

Immunopathological studies on skin biopsies from 88 patients with rheumatoid arthritis showed that one-third of them had deposits of IgM and/or C3 in the walls of small vessels immediately underneath the dermal-epidermal junction. The deposits in the vessel walls which may reflect subclinical immune complex vasculitis could be correlated to the occurrence of IgG-rheumatoid factor in the serum, but not to IgM-rheumatoid factor, other extra-articular manifestations, or to the occurrence of circulating immune complexes demonstrated by the complement consumption test or the thrombocyte aggregation test. Two untreated patients had granular deposits in the dermal-epidermal junction. Five out of 50 patients developed deposits in the dermal-epidermal junction during treatment with levamisole, penicillamine, or azathioprine, as observed by serial skin biopsies.