Peptide in Murine Leukemia Vaccination with Multiple Antigen Peptide as Rejection Antigen

pRLla (IPGLPLSL) is the Ld-binding tumor rejection antigen peptide recognized by ("l'I.s on »VI,ISA-radiation leukemia KI I. We demon strated that in vivo and in vitro sensitization with pRLla multiple antigen peptide (MAP), but not with the pRLla peptide itself, generated pRLlaspecific CTLs in the spleen cells of BALB/c mice. No enhancement of cytotoxicity was observed by emulsifying pRLla MAP in incomplete Freund's adjuvant or in complete Freund's adjuvant for in vivo sensiti zation. Selective depletion of ('I)-T T cells in mice by treatment with anti-L3T4 (CD4) monoclonal antibody and that of macrophages by treat ment with carrageenan on in vivo sensitization with pRLla MAP abro gated ( "l'I. generation. The findings suggest that ( IM ' T cells and anti gen-presenting cells were necessary for the in vivo priming of CD8+ T cells with pRLla MAP. Furthermore, we demonstrated that in vivo sensitiza tion of BALB/c mice with pRLla MAP, but not with pRLla peptide, showed an inhibitory effect on RLá 1 tumor growth. No growth-inhibitory effect was observed on control RVA, RVD, or Meth A tumors.