AMD3100 does not mobilize APL cells from the peritoneal cavity. (A) Kinetics of APL progression following intraperitoneal administration of APL cells. Syngeneic B6129F1 recipient mice (n = 10) were injected intraperitoneally with 10⁶ APL cells and the percentage of Gr-1⁺CD34⁺ APL cells in the peritoneum, peripheral blood, spleen, and BM was determined weekly by flow cytometry. APL cells expanded into the peritoneal cavity during the first 2 weeks followed by engraftment in the BM and spleen during the third and fourth weeks. (B,C) Fifteen (B) or 22 (C) days after APL injection, leukemic mice were treated with a single subcutaneous dose of 5 mg/kg AMD3100 and killed 3 hours later. Baseline peritoneum and peripheral blood samples were collected immediately before (pre-AMD) administration of AMD3100. AMD3100-mobilized APL cells into the peripheral blood (B) during the fourth week, but not from the peritoneal cavity (A) during the second week.