We investigated the induction of the specific immunity for renal cell carcinomas (RCC) using MN/CA IX, a tumor-associated antigen frequently expressed in RCC. We have generated 9-mer peptide derived from MN/CA IX and examined the antigenicity as a vaccine to induce specific immunity for RCC. To use mouse syngeneic system, we transfected human MN/CA9 cDNA into RenCa and BALB-3T3 cells originally from BALB/c mouse, and established MN/CA IX expressing mouse cell lines, i.e., MN-RenCa and MN-3T3. The immunization of BALB/c mouse with MN-RenCa cells resulted in the induction of cytotoxic T lymphocytes (CTL) against MN/CA IX expressing cells and the CTL clone was established from bulked CTL. This CTL clone specifically lyzed MN-3T3 cells, but not parental cells. To identify the targeted epitope binding to H-2Kd antigen, three 9-mer peptides (A, B, C-peptide) of human MN/CA IX compatible with the H-2Kd as well as HLA-A24 binding motif was synthesized. The cloned CTL targeted the B-peptide pulsed BALB-3T3 cells as well as MN-3T3 cells. Furthermore, spleen cells from BALB/c mouse immunized with B-peptide reacted against MN-RenCa cells. These results suggest that the peptides derived from MN/CA IX containing HLA-A24 binding motif may be useful as a potent tumor vaccine for the treatment of human RCC, and in mouse models.

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