Differential cytotoxicity of tumorigenic and nontumorigenic strain-2 guinea pig cells as mediated by syngeneic phytohemagglutinin-stimulated peritoneal exudate cells.

Phytohemagglutinin (PHA)-stimulated peritoneal exudate (PE) cells from strain-2 guinea pigs were more cytotoxic in culture to syngeneic tumorigenic cells than to syngeneic nontumorigenic cells. Cytotoxicity was measured by the release of 3H-thymidine from prelabeled target cells. Tumor-producing guinea pig fetal cells transformed in culture by chemical carcinogen released up to 70 percent of their label in the presence of PHA-stimulated PE cells. Non-tumor-producing cells, regardless of their morphologic characteristics, were less affected by PHA-stimulated PE cells. Nontumorigenic cultures included untreated early passage and long-term cultures previously treated with a carcinogenic or noncarcinogenic chemical. Differential cytotoxicity to tumorigenic cultures were best distinguished from nontumorigenic cultures when 0.5-1 times 10-6 PE cells and 50-100 mug PHA were incubated with 1 times 10-4 3H-thymidine-labeled target cells for 48 hours.