Identification of effector T cells responsible for enhanced antitumor immunity induced by tumor vaccine and pyran copolymer

Summary The combination of concanavalin A-bound, but not concanavalin A-free, L1210 murine leukemia vaccine and pyran copolymer produced an enhanced therapeutic response in L1210-bearing mice. Immunoprophylactic experiments showed that the effective combination produced enhanced antitumor immunity as determined by refractoriness to the inoculation of live L1210 cells. In vitro antiproliferation and intraperitoneal adoptive transfer tests showed that antitumor effector cells were detected in the spleen and peritoneal cavity of primed mice after, but not before, live L1210 cell inoculation. These effector cells were identified as T cells on the basis of their non-adherence to plastic flasks and sensitivity to treatment with anti-mouse brain-associated T cell antigen antisera and complement. Although non-T cell populations, including macrophages of mice primed with L1210 vaccine and pyran copolymer, inhibited the in vitro proliferation of L1210 cells, we obtained evidence suggesting that they were not the primary antitumor effector cell populations responsible for the in vivo elimination of the inoculated L1210 cells.