Antibody-dependent direct cytotoxicity of human lymphocytes. I. Studies on peripheral blood lymphocytes and sera of patients with systemic lupus erythematosus.

Antibody-dependent direct cytotoxicity (ADDC) is generally believed to be unrelated to T-cell function in experimental animals. The role of ADDC in humans and its clinical usefulesss was evaluated in patients with systemic lupus erythematosus (SLE) and normal controls. Peripheral blood lymphocytes from patients with active SLE were unable to lyse antibody-coated target cells in vitro to the same degree as lymphocytes from patients with inactive SLE and controls. Sera from patients with active SLE suppressed ADDC by lymphocytes derived from normal controls and this abnormality was not corrected by overnight incubation or by extensive washing of lymphocyte preparations. Although there was poor correlation between ADDC and the proportions of B cells and null cells in effector lymphocyte populations from SLE patients and controls, it is concluded that this assay provides another means of determining immune competence in man.