CXCR4 mediates homing and repopulation of NOD/SCID mice by R4⁻ cells.

(A) Transplantation of R4⁻ cells at day 0 (▪, left panel), followed by antihuman CXCR4 mAb intraperitoneal injection at the indicated time points (■, left panel). R4⁻ cells cultured with 5-cytokine combination for 24 hours (middle panel) or 48 hours (right panel) were coinjected without (▪) or with (■) anti-CXCR4 mAb (10 μg/mouse). Engraftment levels were determined 5 to 6 weeks later. Data present mean ± SE values of 3 independent experiments, 4 mice per group; P < .05. (B) Representative FACS analysis of BM samples of highly engrafted mice that received transplants of R4⁻ cells cultured for 48 hours with 5 cytokines. (Bi) Cells injected without (Bi-Bii) or with (Biii) anti-CXCR4 mAb (10 μg/mouse). Samples were stained with antihuman CD45 and CD19 (Bi, Biii) or CXCR4 (Bii). (C) Homing of R4⁻ cells and enriched CD34⁺ cells into the BM and spleen of NOD/SCID mice that underwent transplantation at indicated time points; P < .05. Three experiments are summarized. (D) Representative FACS analysis of homed human cells to the murine BM. (Di) R4⁻ cells, time 0, before transplantation. (Dii) Nontransplanted mouse BM. (Diii) A mouse that received a transplant of total CD34⁺ cells (16 hours following transplantation). (Div) A mouse that received a transplant of R4⁻ sorted cells, time 0 sorted cells and cells in the murine BM 29 hours following transplantation.