Reversal of CD8(+) T cell ignorance and induction of anti-tumor immunity by peptide-pulsed APC

In the present report, we have studied the potential of naive and activated effector CD8(+) T cells to function as anti-tumor T cells to a solid tumor using OVA-specific T cells from TCR-transgenic OT-I mice. Adoptive transfe r of naive OT-I T cells into tumor-bearing syngeneic mice did not inhibit t umor cell growth. The adoptively transferred OT-I T cells did not prolifera te in lymphoid tissue of tumor-bearing mice and were not anergized by the t umor. In contrast, adoptive transfer of preactivated OT-I CTL inhibited tum or growth in a dose dependent manner, indicating that E.G7 was susceptible to immune effector cells. Importantly, naive OT-I T cells proliferated and elicited an anti-tumor response if they were adoptively transferred into no rmal or CD4-deficient mice that were then vaccinated with GM-CSF-induced bo ne marrow-derived OVA-pulsed APC, Collectively, these data indicate that ev en though naive tumor-specific T cells are present at a relatively high fra ction they remain ignorant of the tumor and demonstrate that a CD8-mediated anti-tumor response can be induced by Ag-pulsed APC without CD4 T cell hel p.