Studies of allograft immunity in mice. II. Mechanism of target cell inactivation in vitro by sensitized lymphocytes.

Abstract

The mechanisms of the in vitro interaction of sensitized lymphocytes and allogeneic target cells has been studied in a tumour allograft system in inbred mice. The cytotoxic effect of sensitized lymphocytes is shown to require the presence of Ca+ + and Mg+ +. Pretreatment of the lymphocytes with trypsin led to inhibition of cytotoxicity, followed by spontaneous reversal after 1–3 hours incubation. Reactivation was found to be blocked by an inhibitor of protein synthesis (cycloheximide). Cortisone was not found to inhibit the lytic interaction significantly; an occasional effect is thought to be due to toxicity of cortisone for lymphocytes as revealed by dye exclusion test. Inhibition of DNA-synthesis with FUdR (an inhibitor of the enzyme thymidine synthetase) did not reduce the lytic activity of sensitized lymphocytes.