PHA-induced cytotoxicity of human lymphocytes against adherent hela cells

The conditions for a phytohaemagglutinin(PHA)-induced cytotoxicity test of human peripheral blood lymphocytes were investigated. [3H]thymidine prelabelled HeLa cells were used as target cells. Stimulation with 10 microliter PHA/ml during 24 h gave the best measure of lymphocyte cytotoxic capacity. Supernatants of PHA-activated lymphocytes showed no cytotoxicity against adherent HeLa cells. Mitomycin treatment did not influence cytotoxic capacity. Removal of phagocytizing mononuclear cells reduced spontaneous cytotoxicity, but increased PHA-induced cytotoxicity. Adherent cells showed high spontaneous cytotoxicity, with little increase on addition of PHA. The method was evaluated for clinical applicability by testing mononuclear cells from 19 normal subjects and purified lymphocytes from 15 normal subjects. Purified lymphocytes showed a higher PHA-induced cytotoxicity with a smaller variation and greater ratio dependent increase in cytotoxicity than unseparated mononuclear cells. Results with fresh purified lymphocytes were reproducible.