RA enhances the expression of α4β7 and CCR9 on donor T cells in mesenteric lymph nodes. Lethally irradiated Balb/c mice were transplanted with B6 BM and spleen cells and treated with either DMSO or RA. Mice from both groups were killed at day 7 after BMT. The expression of integrin and chemokine receptors on donor T cells isolated from different secondary lymphoid tissues of recipient mice was examined by gating on donor-derived H-2K^b+ CD4⁺ or H-2K^b+ CD8⁺ cells. (A) Representative contour plots for CCR9 and α4β7 expression on donor T cells isolated from MLNs. (B) Mean percent positive (± SEM) donor T cells expressing CCR9 and α4β7 isolated from MLNs (n = 6-8 per group). Statistics: ***P ≤ .001. (C) Recipient mice were treated with either DMSO or escalating doses of RA, the expression of CCR9 and α4β7 on donor T cells from the MLNs of recipient mice 7 days after BMT is depicted (n = 3 per group). Data are from 1 of 2 representative experiments. (D) Representative contour plots for CXCR3 and CCR5 expression on donor T cells isolated from spleen. (E) Mean percent positive (± SEM) donor T cells expressing CXCR3 and CCR5 isolated from spleen (n = 6-8 per group). (F, G) Mean percent positive (± SEM) donor T cells expressing CCR10 (F) and gut-homing molecules (G) isolated from peripheral lymph nodes (n = 6-8 per group). Data are combined results from two independent experiments. Statistics: *P ≤ .05, **P < .01.