Killer cell function of antibody-dependent cell-mediated cytotoxicity in systemic lupus erythematosus

Peripheral blood lymphocytes from patients with systemic lupus erythematosus were compared with those of normal donors for their ability to perform antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC activity was significantly decreased (p<0.001) in active SLE. Correlations appear to exist between either disease activity, CH50 or lymphocyte counts, and ADCC activity. There was no apparent relationship between ADCC activity and the level of corticosteroid administered. Also, no significant correlation was demonstrated between ADCC activity and the levels of circulating immune complex (CIC).Sera from patients with SLE inhibited ADCC activity of the normal lymphocytes. A close relationship was observed between the inhibitory effect of SLE sera on the ADCC of the normal lymphocytes and CIC levels. Sera containing CIC inhibited ADCC of the autologous lymphocytes from the patients. No correlation was observed between ADCC activity and the serum-mediated inhibition of ADCC of normal lymphocytes. These results suggest that the decreased ADCC activity in SLE patients is partly due to the killer cell dysfunction as well as to the suppressive effect of CIC on the ADCC.