Figure 5.
Immunotherapy of peripheral MC-GP tumors. Mice with growing MC-GP tumors of ≥5 mm on day 14 after transplantation were selected for immunotherapy experiments; tumor growth after the different priming strategies was followed up to 100 days. Closed circles indicate animals from the different experimental groups and open circles represent untreated control animals (a–f). The numbers shown indicate the proportion of tumor growth (or/rejection) per tumors tested. Each experiment was repeated twice with similar results. A low dose of LCMV (2 × 102 pfu) (a) or a high dose (2 × 106 pfu) (d) was injected intravenously 14 days after transfer/transplantation of tumor cells; this time point is now taken as day 0 of therapy. The day of transplantation is indicated as ▴. Dendritic cells were isolated from GP33–41 transgenic mice (H-8) (22) (GP33-DC) and injected either once on day 0 (b) or repetitively during 3 weeks as indicated (e) (105 cells per injection). MC-GP cells were also injected once (c) or repetitively every other day during 3 weeks (2 × 106 cells per injection) (f). The outcome of all performed experiments is summarized in g. All the treated animals mounted a CTL response when tested in a 51Cr release assay after in vitro restimulation, whereas the untreated controls did not (h). (●), CTL response of animals 40 days after the beginning of the immunotherapy; (○), animals without immunotherapy.