Clonogenic potential and phenotypic analysis of CD34(+) cells mobilized bydifferent chemotherapy regimens

Background and Objective. Since limited data concerning quantitative and qu alitative differences of CD34(+) cells collected after different mobilizati on schedules are available, we investigated phenotype, proliferative capaci ty and primitive progenitor cell content of CD34(+) cells mobilized with fo ur different regimens. Design and Methods. The number, phenotype, and progenitor cell content of C D34(+) cells were investigated in 46 patients mobilized with cyclophosphami de (CY) 7 g/m(2) plus granulocyte colony-stimulating factor(G-CSF, 5 mu g/k g) (CY7+G-CSF) (n=16), CY 4 g/m2 plus G-CSF (CY4+G-CSF) (n=8), IVE [ifos-ph amide (2.5 g/m(2) for 3 d), etoposide (150 mg/m(2) for 3 d), epirubicin (10 0 mg/m(2) on day 1)] plus G-CSF (IVE+G-CSF) (n=9), or G-CSF (10 mu g/kg) al one (n=13). Results. The number of CD34(+) cells collected per liter of processed blood was significantly higher in the CY7+G-CSF group than in the CY4+G-CSF and G-CSF groups (p less than or equal to .005), but not the IVE+G-CSF group. A s compared to patients in the CY4+G-CSF group, those mobilized with CY7+G-C SF and IVE+G-CSF produced significantly lower percentages of CD34(+) cells lacking CD38, CD33, CD45RA, and HLA-DR (p less than or equal to .016, at le ast). In addition, CY4+G-CSF mobilized CD34(+) cells had a significantly hi gher plating efficiency than the cells mobilized in other ways (p less than or equal to .036). In the G-CSF group, colony-forming cells and long-term culture-initiating cells were significantly lower than in the CY groups (p less than or equal to .0014 and less than or equal to .013, respectively). Interpretation and Conclusions. Our data demonstrate that: (i) different mo bilization regimens allow the collection of CD34(+) cells with distinct phe notypic and proliferative features; (ii) evaluation of the absolute number of CD34(+) cells by itself is not a reliable indicator of the clonogenic co ntent of blood mobilized with different chemotherapy regimens; (iii) becaus e of the substantial impact that chemotherapy regimens have on the quantity and quality of collected CD34(+) cells, anticancer effects and optimal blo od progenitor cell yields should be evaluated for each chemotherapy schedul e. (C) 1999, Ferrata Storti Foundation.