CD8+ T-cell mediated anti-tumor responses cross-reacting against 9L and RT2 rat glioma cell lines.

We have shown that vaccination of animals with two distinct commonly used glioma cell lines, 9L and RT2, generated cross-reactive cellular anti-tumor immunity. Peripheral vaccination with either cell line 9L or RT2 resulted in MHC Class I restricted effector cells capable of in vitro cytolytic activity against both target 9L and RT2 cells but not the syngeneic F98 glioma cell line. In vitro cross-reactive cytolytic activity could be measured for as long as 6 months from the time of initial vaccination. Fractionation of splenic effector cells revealed the cytolytic activity to be CD8+ T-cell mediated but required CD4+ T-cells for effective antigen presentation. Anti-tumor immunity generated after vaccination with either 9L or RT2 was completely protective against subsequent subcutaneous inoculation of animals with either 9L or RT2 cells and resulted in prolonged survival in animals inoculated intracranially with either cell line. Our results suggest that despite the different methods used in their derivation, 9L and RT2 glioma cells share a common glioma antigen recognized by the cellular arm of the immune response.