Phytohemagglutinin-induced cytotoxic action of normal lymphocytes on cells in tissue culture using 14C-leucine incorporation.

Stimulation of normal peripheral blood lymphocytes (PBL) by phytohemagglutinin (PHA) and production of PHA-induced cytotoxicity were investigated. PBL transformation stimulated by PHA was measured by 3H-thymidine incorporation, and the cytotoxicity was assayed by measuring the reduction of 14C-leucine incorporation in to target cells after interaction with PHA-treated PBL. The cytotoxicity of PHA-treated PBL showed dose response curves which corresponded with that of PBL transformation. Reduced 14C-leucine incorporation of target cells caused by cytotoxic PBL would be a reliable measure of immune reactions.