Defective maintenance of CXCR5 ⁺ stem-like CD8 ⁺ T cells in the absence of TGF-β without apparent defects in viral clearance or pathology. Similar experimental setup to Fig. 1. One group of mice received CD4 depleting antibody 1 d before and 1 d after infection. (A) The percentage of CXCR5⁺ cells in donor P14 T cells are shown at indicated time points. (B) Day 15 after infection, representative FACS profiles of pre-gated donor P14 T cells are shown (two independent repeats, n = 5/each). Each pair of symbols in A represents the results from an individual recipient. Pooled results from two independent repeats are shown in A (n = 5/each). P values were calculated by paired Student’s t test. WT and Tgfbr2^−/− P14 T cells were separately transferred into B6 recipients followed by LCMV Cl13 infection. (C and D) Day 10 (C) or day 25 (D) after infection, representative H&E staining of different tissues are shown (n = 3/each, two repeats). (E) Day 25 after infection, immunohistochemistry of liver sections to show LCMV antigen (blue). n = 3/each, two repeats. (F) Day 18 after LCMV Cl13 infection, spleen sections were examined by immunohistochemistry. Top, negative staining control without primary antibody; bottom, staining with primary antibody (two independent repeats, n = 2/each). Black arrows indicate intra-follicle TGF-β producing foci, and blue ones indicate extra-follicle TGF-β producing foci.