FIG. 2.

CD8⁺ T-cell killing in vivo. CFSE-labeled Friend virus-induced FBL-3 tumor cells (FV tumor) were injected subcutaneously into naïve, acutely infected (2 weeks postinfection), persistently infected mice (8 weeks postinfection). As controls CFSE-brightly labeled Friend virus negative EL-4 (non-FV tumor) tumor cells were coinjected. The tumor cells were harvested 24 h after injection and analyzed for CFSE fluorescence. The figures show the results of a representative mouse from each group (three mice per group) with the numbers representing the percentages of target cell killing.