miR-17∼92 regulates CD8 T-cell expansion and the balance between effector and memory fates. CKO and CTg mice with conditional loss or gain of expression of miR-17∼92 after activation of GZMB, respectively, were infected with LCMV along with wild-type mice, and antigen-specific CD8 T-cell responses were measured longitudinally in peripheral blood mononuclear cells. (A) Total antigen-specific CD8 T-cell responses were enumerated by flow cytometric analysis of CD44^hi CD8⁺ T cells. Representative dot plots depicting frequencies of CD44^hi CD8 T cells at the effector peak (day 8) and memory phase (day >30) are shown. (B) Representative dot plots of D^bGP33-, D^bNP396-, and D^bGP276-specific CD8 T cells are shown at day 8 after infection. Numbers indicate the frequency of tetramer-positive CD8 T cells. (C) Line charts depict the frequencies of CD44^hi and tetramer-specific CD8 T cells at indicated times after infection. (D) Bar graphs show total numbers of IFN-γ⁺ antigen–specific CD8 T cells at memory after 5-hour in vitro stimulation of splenocytes with indicated epitope peptides (0.1 μg/mL). Representative data from one experiment containing 3 mice in each group are presented. Unpaired Student t test was used for analysis of statistical significance (*P ≤ .05). (E) Representative dot plots of CD127 and KLRG-1 gated on tetramer-positive CD8 T cells are shown at effector peak (day 8) and memory (day >30) phases. Numbers in FACS plots represent quadrant frequencies. Mean ± SEM values of percentage MPECs (CD127⁺ KLRG-1^–) and SLECs (CD127^– KLRG-1⁺) are plotted as line charts. Representative data from 1 experiment containing 3 mice in each group are presented. Unpaired Student t test was used for analysis of statistically significant differences between wild-type and CKO or CTg mice, respectively (*P ≤ 0.05, **P ≤ .01, ***P ≤ .001).