The use of phagocytic peritoneal exudate cells as targets for the estimation of cytotoxic T cell activity

A new method for measuring cytotoxic T lymphocyte (CTL) activity has been developed with peritoneal exudate cells (PECs) as target. A monolayer of target PECs was labelled with Indian ink and exposed to CTL. After incubation, detached or damaged PECs were rinsed out of the target monolayer, and the remaining phagocytes were fragmented and dissolved by the addition of 2 N NaOH. The number of undamaged target cells was estimated by colorimetric reading of the amount of Indian ink in the phagocytes surviving CTL attack. In studies with several strains of mice, only PECs from the same strain as the stimulator cell donors used for CTL induction were damaged by CTL effectors. When CTLs generated against TNP-modified syngeneic stimulators were used as effectors TNP syngeneic PECs, but neither unmodified syngeneic PECs nor allogeneic TNP-PECs, were damaged. These results demonstrate the antigen specificity of immunolysis of PECs. Macrophage target cells were stable and showed no tendency to spontaneous cell damage during 24 h incubation without effector cells.