A sensitive method to measure PHA-induced cytotoxicity to adherent target cells using [3H]uridine as a terminal label.

This paper describes a modification of the PHA-induced cytotoxicity test of human peripheral blood lymphocytes against a tumour-derived adherent cell line (HeLa), in which the surviving target cells are labelled with [3H]uridine at the end of the assay. There is a direct correlation between [3H]uridine incorporation and the number of adherent target cells. The test proves to be very sensitive at low effector; target cell ratios. Frozen stored cells can be used in this system, a particular advantage because of the possibility of increasing the reproducibility of the assay by using the same batch of cryopreserved lymphocytes as a reference standard in each experiment. PHA-induced cytotoxicity was mainly found in the T cell enriched fraction.