Fig. 4.

Recognition of Qa-1–peptide on CD4 T cells by CD8 Treg leads to suppression of CD4 T cell expansion in vitro and in vivo. (A) In vitro suppression analysis using CD8 Treg [CD44⁺CXCR5⁺CD8⁺] sorted from naïve WT mice as effector cells, and CD25^–CD4⁺ T cells sorted from naïve D227K or WT mice as target cells. Proliferation was measured by tracing CellTrace Violet, with representative gating at each effector to target cell ratio shown on the right (n = 6 and 8 for D227K and WT target cell donors respectively, two-way ANOVA test followed by Tukey’s multiple comparison test). The data shown are representative of two independent experiments. (B) In vivo suppression assay using RAG1^−/− hosts with adoptive cell transfer of B cells, CD4 T cells, and CD8 Treg. (C) Percentage (%) of T_FH in CD4 cells from host spleens at day 10 after adoptive transfer (n = 8 per group; unpaired t test) in group 2 compared to group 1. *P < 0.05; **P < 0.01.