Natural killing in systemic lupus erythematosus: inhibitory effects of serum.

Abstract The natural killing (NK) of a tumor cell line, K-562, was studied using lymphocytes of patients with systemic lupus erythematosus (SLE) and normal subjects. NK varied greatly in both populations but was significantly decreased in those patients with untreated SLE 17 ± 5%, versus those patients with treated SLE, 44 ± 15% and controls, 44 ± 13%. The NK of SLE cells increased following overnight incubation, suggesting the role of membrane-bound factors. Serum from patients with untreated SLE markedly inhibited NK (45 ± 17%) in contrast to control sera (2 ± 3%). A significant correlation was found between the NK of a given patient and the inhibition by autologous sera of the NK of mononuclear cells from normal subjects.