CXCR3^−/− memory CD8⁺ T cells display a high memory potential phenotype. (A–D) 1 d after transfer of mixed CXCR3^−/− and WT OT-I cells, recipient mice were infected with VV-OVA as in Fig.1 B. (A and B) Surface expression of indicated markers on CXCR3^−/− and WT OT-I cells in the spleen was analyzed on day 99 after infection. (C) Numbers of CD127^hi KLRG1^lo cells in the spleen at day 99 are shown as mean ± SEM. *, P < 0.05. (D) Expression of CD27 and CD122 on splenic OT-I cells at the same time point. Numbers to the right of the CD122 plots indicate the MFI and MFI ratio of CXCR3^−/− to WT. (E) 70+ d after transfer, the recipient mice containing both CXCR3^−/− and WT memory OT-I cells were administered BrdU for 17 d. (F and G) CXCR3^−/− and WT memory OT-I cells were generated in separate hosts as shown in Fig. 2 D. On day 40+ after infection, OT-I cells were isolated from spleen, labeled with CFSE, and co-transferred into naive nonirradiated recipient mice. (F) Homeostatic proliferation was determined by CFSE dilution 17 d after transfer. Histograms gated on OT-I cells show the ratio of CXCR3^−/− and WT OT-I cells at transfer (day 0) and day 17 after transfer, and CFSE dilution. (G) Number of OT-I cells in spleen. Data are shown as mean ± SEM. Data represent three (A–D) or two (E–G) independent experiments (n = 3–4).