Direct lysis of lymphocytes by complement in patients with systemic lupus erythematosus

Lymphocytes from patients with active systemic lupus erythematosus (SLE) were found to undergo lysis when exposed to rabbit complement. A simple test procedure for quantitating this phenomenon was devised. In patients with active SLE and severe leukopenia, lymphocytes dropped to 29% after incubation with complement. The mean percent survival of lymphocytes from 15 patients with active SLE was 52 (21–78%). In 50 control subjects there was little or no decrease in the number of lymphocytes after exposure to complement. The results suggest that circulating lymphocytes of patients with active SLE may be coated with autoantibody rendering them susceptible to lysis upon addition of complement.