CD8+ T cells are required for allogeneic rejection of Meth A tumor cells. C57BL/6 mice (H-2^b) were challenged intradermally with 2 x 10⁶ live Meth A cells (H-2^d). To deplete various T cell subsets, the indicated antibodies or RPMI were injected at the time of tumor challenge, and each week thereafter, in the retro-orbital sinus. Tumor diameter was measured every two to three days. Each line represents the average measurement of five mice.