The elevated CXCL12 expression promotes recruitment/retention of Treg and hematopoietic stem cells in the bone marrow. A. Comparison of the percentages and numbers of Foxp3+CD4+ Tregs in the bone marrow between age-matched Balb/c (n = 7) and prediabetic NOD (n = 20) mice (15 weeks of age). Bone marrow cells were assayed for TCR, CD4 and Foxp3. Tregs are identified as TCR+Foxp3+CD4+ cells. The percentage value of Foxp3+ cells is expressed as percent of CD4+ T cells. B. Effect of CXCR4 deletion on Treg distribution in the spleen and bone marrow. Cells from spleen and bone marrow of Cxcr4f/fLck-Cre (KO) mice and littermate Cxcr4+/fLck-Cre (WT) (8 weeks of age) were assayed for TCR, CD4, CD25 and Foxp3. The numbers of TCR+CD4+CD25+Foxp3+ cells are compared in the spleen and bone marrow from 3 mice per group. C. Comparison of numbers of hematopoietic stem cells (Lin-Sca1+c-Kit+, LSK) among age-matched Balb/c (n = 5), prediabetic NOD (n = 5) and AMD3100-treated (8 days) prediabetic NOD mice (n = 4). *p < 0.05.