Antibody-dependent direct cytotoxicity of human lymphocytes. II. Studies on peripheral blood lymphocytes, synovial fluid cells and sera from patients with rheumatoid arthritis.

Antibody-dependent direct cytotoxicity (ADDC) by human lymphocytes was evaluated in patients with rheumatoid arthritis and normal controls. Purified peripheral blood and synovial fluid lymphocytes mediated normal ADDC when compared to control subjects. No correlation could be obtained between the percentages of T, B and null cells in effector cell populations and the degree of 51Cr released from target cells. Sera from 50% of patients with rheumatoid arthritis inhibited ADDC by normal lymphocytes; the degree of inhibition did not correlate with the titre of IgM rheumatoid factor. The pathogenic implications of these findings are discussed.