Relationship between cytotoxic T-lymphocytes and suppressors blocking activation of DNA synthesis in mixed lymphocyte cultures]

Cytotoxic T-lymphocytes (CTL) and suppressors induced by immunization in the H-2 system and inhibiting DNA synthesis activation in mixed lymphocyte culture were studied in parallel. Unlike CTL, suppressors did not adhere specifically to the target cell monolayer, they were not inactivated by anti-theta serum plus complement, and their action was not specific: they inhibited the DNA synthesis activation stimulated by any stimulant cells, as well as by phytohemagglutinin and concanavaline A. CTL and suppressors proved to represent different effector cell populations which could be separated from one another.