CXCR4 is highly expressed on T cells of AA mice. F1 hybrid mice were irradiated only (γIR control) or AA was induced with 5 × 10⁷ WT C57BL/6 splenocytes. Mice were sacrificed on day +17 postdisease-induction and T cells were isolated. (A) Relative expression of Cxcr4 transcript levels in T cells from spleens (BMF spleen) and BM (BMF BM) of AA mice were determined by quantitative PCR and compared with expression in T cells of spleens (γIR spleen) from irradiation controls; n = 13 mice per group. (B) Median fluorescence intensity (MFI), a measure of CXCR4 protein expression, on spleen and BM T cells of AA mice was determined by flow cytometry and compared with expression on spleen T cells of irradiated controls; n = 13 mice per group. (C) Representative comparative histograms of CXCR4 MFI on T cells from spleens and BM from (B). (D) Percent CXCR4 positive T cells on T cells from spleens and BM of AA mice, compared with T cells isolated from spleens of irradiation controls; n = 13 mice per group. (E) Comparison of CXCR4 expression on BM-infiltrating CD4⁺ and CD8⁺ T cells of AA mice; n = 13 mice per group. Data represent the mean ± SEM, and were analyzed by one-way ANOVA plus Tukey post-test (A-B,D), or two-tailed unpaired Student t test (E). *P < .05; **P < .01; ***P < .001.