Deficient interleukin-2-activated killer cell cytotoxicity in patients with systemic lupus erythematosus

This study was undertaken to determine if the cytotoxic activity of interleukin-2 (IL-2)-activated killer (LAK) cells, which is induced by the direct activation of lymphocytes by IL-2, is defective in systemic lupus erythematosus (SLE). The killer cell activity of SLE patients, whether it be generated in autologous plasma or serum-free media, was significantly less than the controls against three different target cells. It was observed, by incubating control lymphocytes in 10% fresh SLE plasma, that soluble factors were responsible for a portion of the reduced generation of LAK cell cytotoxicity (P less than 0.05). Suppression ranges from 4 to 70% with a mean of 33%. However, when SLE LAK cells were generated in serum-free media, a greater reduction of generated LAK cell activity was observed (P less than 0.005). Using a disease activity score, it was determined that SLE cytotoxicity negatively correlated with disease activity only when the cells were cultured in serum-free media. Irrespective of the culture conditions, lytic activity did not correlate with levels of anti-DNA antibodies, anti-Sm antibodies, circulating immune complexes, or prednisone therapy.