Natural cell mediated cytotoxicity in autoimmune diseases

Abstract

The significantly reduced natural killer (NK) cell activity was demonstrated in the peripheral blood lymphocytes (PBL) from 20 female patients with systemic lupus erythematosus (SLE) when compared with NK activity in the age- and sex-matched controls. The reduced NK activity did not correlate with clinical parameters including daily prednisolone doses, serum CH50, antinuclear antibody titers, anti DNA activities, circulating immune complex levels and cytotoxic activities of antilymphocyte antibodies (ALA). The effects of prednisolone and aggre-gated human IgG on NK activity were only slightly suppessive in the in vitro studies. When normal PBL were pretreated with rabbit complement and SLE sera containing ALA, the NK activity of the surving cells was markedly decreased. The decrease was specific and did not seem to be due to physical hindrance of the dead cells. Other heterologous ALA of rabbit origin did not exert a suppressive effect on NK activity. These results suggest that the suppressed NK activity in SLE may possibly be ascribed to an anti NK cell specific antibody in lupus sera although the participation of circulating immune complexes was not completely excluded.