Antitumor protection using murine dendritic cells pulsed with acid-eluted peptides from in vivo grown tumors of different immunogenicities

Peptides extracted from tumor cells after mild acid treatment can function as antigenic epitopes when presented by cultured dendritic cells. Peptides were extracted from foul tumors syngeneic to C3H mice, three weakly immunog enic tumors (FSA, MCAK, HCA) and one non-immunogenic tumor (NFSA). Dendriti c cells pulsed with peptides extracted from the three weakly immunogenic tu mors partially protect mice from a tumor challenge with the parental cell l ine. This protection was evident by a slower rate of tumor appearance and a slower tumor growth curve when compared to control, non-immunized mice. Ho wever, vaccination of mice with dendritic cells pulsed with peptides derive d from the non-immunogenic cell line NFSA did not elicit a protective respo nse. Neither the route of immunization, the number of immunizations, nor th e amount of peptides significantly affected the antitumor protection. Dendr itic cells genetically engineered to produce IL-2 did not increase the prot ective effect of peptide-pulsed dendritic cells. These results suggest that only a partial protection against immunogenic tumors can be achieved when dendritic cells pulsed with acid-eluted tumor peptides are used as antitumo r vaccination.