DIFFERENTIAL PRESENTATION OF ENDOGENOUSLY PROCESSED CYTOTOXIC T-LYMPHOCYTE EPITOPES BY MOUSE HEPATOCARCINOMA CELL-LINES INDUCED BY SV40 LARGE T-ANTIGEN

Tumor cells can have different morphologic or metabolic phenotypes and display genetic instability. Thus they could also vary in their abili ty to present epitopes to the immune system, We have analyzed the pres entation of H-2K(b)- and D-b-restricted cytotoxic T lymphocyte (CTL) e pitopes of a tumor-associated antigen by three cell lines derived from hepatocarcinomas developed in vivo by mice transgenic for SV40 T targ eted to the liver, SV40 T is the obvious tumor-specific antigen and ep itopes derived from this antigen were therefore studied, The study inc luded four already known epitopes that can be presented by SV40-transf ormed kidney cells and two new CTL epitopes that were identified in th e present work, CTL lines specific for each epitope were obtained from C57BL/6 mice and were used to map the presentation of SV40 T peptides by the hepatocarcinoma cells. These tumor cells were derived from the same tissue, induced by the same agent and all naturally presented pe ptide p232-240 from p53, Despite these common features, they all had d ifferent patterns of spontaneous presentation of SV40 T CTL epitopes, The mechanisms underlying this disparity are discussed, together with the possible consequences for establishing immunotherapeutic strategie s.