Characteristics of a cytotoxic human lymphocyte-dependent antibody

Lymphocyte-dependent antobody (LDA) from the blood of a patient with choriocarcinoma was characterized in an allogeneic in vitro system. The antibody reacted with specific traget cells, including cells from the patient's husband. Antibody-coated traget cells were damaged by normal lymphocytes from man and other species. Neither cytotoxic, complement-dependent antibody nor sensitized cytotoxic lymphocytes were found in the patient. LDA activity was associated with IgG gamma-globulin by G-200 Sephadex filtration, electrophoretic mobility, and reactivity with anti-IgG, but there was no activity associated with IgM immunoglobulin. Sera from 14 of 16 normal donors lacked detectable LDA activity, and only low levels were found in sera from the other two donors.