Deposits of immunoglobulins and complement C3 in clinically normal skin of patients with lupus erythematosus.

Deposits of immunoglobulins and/or complement C3 were found in two-thirds of biopsies from clinically normal skin of 64 patients with systemic lupus erythematosus, as judged by well defined criteria. The incidence of deposits in clinically normal skin was identical in patients with and without clinical skin lesions. IgM was found more frequently in the deposits (88%) than was IgG (36%) but equally frequently in involved and uninvolved skin, whereas C3 was found more often in patients with skin lesions (59% in involved skin, 36% in uninvolved skin) than in patients without skin lesions (14%). The occurrence of IgG and IgA was less frequent than that of C3 but the distribution was similar to that of C3. In normal skin of 20 patients with chronic discoid LE, deposits were found in one. Deposits were found in the skin of one-third of patients with nuclear antibodies in their sera and symptoms compatible with SLE but with a score of symptoms too low to meet the criteria.