BROAD INTERINDIVIDUAL VARIATIONS IN CIRCULATING PROGENITOR-CELL NUMBERS INDUCED BY GRANULOCYTE-COLONY-STIMULATING FACTOR THERAPY

The elevated white cell counts (WCC) acid myeloid progenitor cell leve ls in the blood induced by granulocyte colony-stimulating factor CG-CS F) treatment were studied in three settings: cancer patients previousl y treated with chemo/radiotherapy (n = 13), untreated cancer patients (n = 5) and normal volunteers (n = 9). The inter-individual variations in progenitor cell mobilization responses to G-CSF and the impact of previous chemo/radiotherapy, were investigated The absolute levels of circulating progenitor cells, but not total white cells, were reduced significantly in the pretreated cancer patients (median 961, range 289 -3355 per ml blood) as compared to untreated cancer patients (median 9 891, range 2219-16625 per ml blood). In each setting, wide ranges of c irculating progenitor cell numbers were observed, and the variation in progenitor cell numbers was considerably greater than observed for th e WCC. However, progenitor cell numbers in normal volunteers (942-2529 6 per ml blood) demonstrated as much variance as observed in pretreate d cancer patients. This broad physiological variation in progenitor ce ll levers induced by G-CSF needs to be considered when designing strat egies for allogeneic peripheral blood stem cell transplantation.