Coinfusion of Tregs with bone marrow diminishes peripheral blood neutrophil numbers after transplantation. (Left panel) B6-wt mice (10-12 weeks old) were lethally irradiated (9.5 Gy TBI) and transplanted with 0.3 × 106 syngeneic TCD-BM. Animals were untreated (n = 7, 2 experiments) or coinfused with 1 × 106 in vivo IL2/anti-IL2 mAb complex–expanded Tregs (> 95% CD4+CD25+) at the time of transplantation (n = 7). Peripheral blood was obtained from animals at days 16 and 17 after HSCT and CBC were performed. Results of 2 independent transplantation experiments are presented. Data of individual mice and the average neutrophil counts/group are shown. (Right panel) PMN levels were obtained from individual transplant recipients as described (n = 4/group). Peripheral blood was obtained at the indicated days after HSCT and 40 μL was analyzed by the Department of Pathology (University of Miami Miller School of Medicine) using a Hemavet 950. There was also an overall decrease in the percentage of PMNs (P < .03) in the peripheral blood (data not shown).
