BC-CML cells promote OT-1 recruitment in the presence of a GVH response. (A) Experimental design. (B) Representative images from the calvarium of mice transplanted as described in panel A; Scale bar represents 50 μm. See also supplemental Videos 8 and 9. (C) Ratios of E/I OT-1 cells. (D) Numbers of extravascular and intravascular OT-1 cells. Symbols connected by lines represent data from the same mice. BM alone data are from 18 volumes from 7 mice. BM + T data are from 15 volumes in 9 mice. We compared the E/I ratios of OT-1 cells in mice transplanted with leukemia cells to those measured in mice transplanted without leukemia cells by normalizing the ratios with leukemia cells to the mean of the ratios observed in mice transplanted without leukemia cells (E). (F-G) The experimental design was similar as in panel A, except intravascular and extravascular OT-1 cells were enumerated by flow cytometry based on extravascular cells staining with αCD45.2 FITC, which was administered 3 minutes before euthanizing. BM cells from femurs and tibias were analyzed. (F) Ratios of extravascular (CD45.2^–) to intravascular (CD45.2⁺) OT-1 cells as determined by flow cytometry. (G) Extravascular OT-1 cell number in BM and spleen. Data are from 2 experiments with 4 mice per group in each. Significance was determined by a 2-tailed Student t test. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. ns, not significant.