Lymphocyte Cytotoxic Antibodies in Systemic Lupus Erythematosus

WE have observed lymphocytotoxic antibodies in sera of patients with connective tissue disorders. The antibodies are cytotoxic to lymphocytes from unrelated random donors using the microcytotoxicity technique 1,2 . The initial studies were done on 161 coded stored sera submitted to the clinical laboratory for routine immuno-electrophoresis, and confirmatory studies were done on forty-seven coded sera selected from patients followed in the clinic for connective tissue disorders. Results of testing of both series of sera are summarized in Table 1 and show that 74 per cent of all sera tested from patients with systemic lupus erythematosus and 14 per cent of sera from patients with rheumatoid arthritis contained lymphocytotoxic reactivity. Appropriate controls indicated that the cytotoxic effect of lupus sera was dependent on complement; fractionation of one lupus serum by anion exchange chromatography indicated that the cytotoxic factor resides among the IgG globulins. Because cytotoxic antibodies are not present in sera of normal persons except in some cases of immunization by multiple transfusions 3,4 , pregnancy 5,6 or organ transplantation 7,8 , the results suggest that lymphocytotoxic antibodies develop during the course of systemic lupus erythematosus.