Interleukin-2 restores the depressed allogeneic cell-mediated lympholysis and natural killer cell activity in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by a variety of profound T-cell abnormalities among which are decreased cytotoxic capacity measured by allogeneic cell-mediated lympholysis (CML), natural killer cell (NK) activity, and decreased lymphokine production. In a group of 13 patients with active SLE, allogeneic CML, tested by a 4-hr 51Cr-release assay, was 18.2 +/- 2.7% while in the group of normal individuals CML was 41.2 +/- 2.7%. If optimal doses of affinity-purified interleukin-2 (IL-2) were present during the mixed lymphocyte culture, the CML of SLE patients was increased to normal levels (40.4 +/- 4.0%). In contrast, interferon-alpha (IFN-alpha) increased (but not significantly) the levels of CML. Mixed lymphocyte reaction, tested by tritiated thymidine incorporation, was also decreased in the group of patients (14,820 +/- 815 cpm vs 28,972 +/- 5880 cpm in normals) and it was increased to normal levels if IL-2, but not IFN-alpha was added to the cultures. NK activity was decreased in the group of patients tested by 51Cr-release assay, harvested at 6 and 18 hr. IL-2 increased the NK activity up to normal levels, while IFN-alpha was only partially efficacious. These results demonstrate that IL-2, but not IFN-alpha, can potentiate or even fully restore the deficient cytotoxic effector function of peripheral mononuclear cells in patients with SLE.