A brief stage of CCR7/CCR9-independent thymic settling after BMT. (A) Lethally irradiated mixed BM chimeras were generated using CD45.2 WT (left column) or CD45.2 CCR7/CCR9 DKO (right column) plus CD45.1 WT competitor cells at a 2:1 ratio (106 total cells). Shown are representative fluorescence-activated cell sorter plots of thymic DP cells at the indicated time points. (B) Mean CD45.2 chimerism ± SEM of BM granulocytes (top row) and thymic DP cells (bottom row) for control WT chimeras (left column) or CCR7/CCR9 DKO chimeras (right column) at the indicated time points after transplant. *P < .05. **P < .01. N = 2 to 14 per group per time point. (C) Experimental design for evaluating the duration of CCR7/CCR9-independent thymic settling after BMT. CD45.1 WT hosts were lethally irradiated and immediately inoculated with CD45.1 BM (2.5 × 105 cells) to ensure survival. After various lengths of time, mice were inoculated with CD45.2 donor BM (either WT or CCR7/CCR9 DKO) and CD45.1 BM at a 5:1 ratio (1.2 × 107 total cells). After 3 additional weeks, BM and thymi were analyzed for donor chimerism. (D-E) Shown is CD45.2 donor chimerism among BM granulocytes (D) or thymic DP cells (E) in mice receiving CD45.2 BM cells at the indicated time points.
