FIG. 4.

Detection of exocytosis in the D^b GagL tetramer+ subset of virus-specific effector CD8⁺ T cells. Flow cytometry was used to detect the degranulation marker CD107a on D^bGagL tetramer-positive effector CD8⁺ T cells. CD8⁺ D^bGagL tetramer+ were gated and analyzed for CD43 and CD107a expression. Activation marker CD43 was used to indicate that all D^bGagL tetramer-positive CD8⁺ T cells were of effector phenotype during both acute (2 weeks postinfection) and persistent (8 weeks postinfection) FV infection. The figures show the results of a representative mouse from each group. Mean percentages of tetramer-positive CD8⁺ T cells that were negative (left) or positive (right) for CD107a are given in the upper quadrants. The mean fluorescence intensities of the CD107a signals were: acute infection = 37.4 (n = 5) and persistent infection = 9.9 (n = 12). The difference between the means is statistically significant (P < 0.0001, unpaired t test). Similar results were obtained in two independent experiments.