Fig. 1.
CD4 T cell precursor frequency affects memory T cell development in response to virus infection. CD45.2 TEa CD4 T cells (1 × 106, 1 × 105, or 1 × 104 cells) were transferred into CD45.1 mice before infection with VSV-SED. (A) The TEa response was assessed at days 7, 16, and 30 after infection. (The asterisk indicates that mice from the 1 × 106 transfers were bled at day 28 after infection.) Numbers indicate the percentage of donor CD4 T cells (CD45.2+) relative to the total CD4 population in the blood. (B) Comparison of the percentage of donor cells within the entire CD4 population in response to VSV-SED when either 1 × 106 or 1 × 105 TEa cells were initially transferred. Days 3, 4, and 5 after infection represent the lymphocyte population from the spleen, whereas days 7, 16, and 30 represent donor CD4 T cells from the blood. (C) The presence of TEa memory cells was determined in the indicated tissues 58 days after infection. (D) The production of IL-2 and IFN-γ by TEa cells (1 × 105 cells transferred) isolated from the spleen 56 days after infection was determined by intracellular cytokine staining after in vitro stimulation with the Eα peptide. The values in the upper right quadrants represent the percentages of positive CD4 cells.