Roles of the ribosomal protein S19 dimer and chemically induced apoptotic cells as a tumor vaccine in syngeneic mouse transplantation models.

We examined the roles of a chemotherapeutic reagent in both inducing apoptosis and conferring acquired tumor immunity using mouse syngeneic tumor transplantation models. A chemotherapeutic reagent, cis-diamminedichloroplatinum (II), effectively induced apoptosis in Colon-26 cells originating from a BALB/c mouse. Three intradermal inoculations of cis-diamminedichloroplatinum (II)-treated Colon-26 cells conferred tumor immunity against viable Colon-26 cells in BALB/c mice but not in athymic BALB/c mice. The acquired immunity was Colon-26 cell specific and was adoptively transferable with splenic cells. We next examined the involvement of the cross-linked ribosomal protein S19 dimer (RP S19), which is released during apoptosis, in the acquisition of tumor immunity. A Colon-26 transformant that produces a Gln137Asn-mutant RP S19 prevents the formation of a functional RP S19 dimer. Acquired tumor immunity was significantly reduced when the transformant was used in combination with anti-RP S19 antibodies as the vaccination source. These data suggest the importance of the RP S19 dimer in chemotherapeutic agent-induced acquired immunity.