Effect of FTY720 and FTY-P on homing and tissue distribution of adoptively transferred T cells. (A-B) TRITC-labeled splenocytes and PLN cells from T-GFP mice were injected intravenously into WT mice (n = 6 mice/group), which had been pretreated 2.5 hours earlier with FTY720, FTY-P, or saline. At different time-points, PBL (1 mL), SLOs, and BM were harvested and single-cell suspensions were analyzed by FACS for the presence of TRITC⁺GFP⁺ T cells. At 2.5 hours after adoptive transfer (A), homed T cells were reduced in PLNs by 44% and 30% in FTY-P– and FTY720-treated mice, respectively, and were increased in PPs by 46% and in BM by 48% after FTY720 treatment. At 16 hours after transfer (B), homed T cells in PLNs remained reduced by approximately 46%. T-cell homing to PPs increased over control: 2.8-fold for FTY-P; 3.9-fold for FTY720; and in BM 3.7-fold for FTY-P; 4.3-fold for FTY720. Data are shown as total number of homed cells per million injected. Error bars indicate SEM. *P < .05; **P < .01 (versus control).