Effects of short-term administration of G-CSF (filgrastim) on bone marrow progenitor cells: analysis of serial marrow samples from normal donors

To determine the effect of G-CSF administration on both the total number of CD34(+) cells and the primitive CD34(+) subsets in bone marrow (BM), we ha ve analyzed BM samples serially obtained from 10 normal donors in steady-st ate and during G-CSF treatment. Filgrastim was administered subcutaneously at a dosage of 10 mu g/kg/day (n = 7) or 10 mu g/kg/12 h (n = 3) for 4 cons ecutive days. Peripheral blood sampling and BM aspirates were performed on day 1 (just before G-CSF administration), day 3 (after 2 days of G-CSF), an d day 5 (after 4 days of G-CSF), During G-CSF administration, a significant increase in the total number of BM nucleated cells was observed. The perce ntage (range) of CD34(+) cells decreased in BM from a median of 0.88 (0.47- 1.44) on day 1 to 0.57 (0.32-1.87), and to 0.42 (0.16-0.87) on days 3 and 5 , respectively, We observed a slight increase in the total number of BM CD3 4(+) cells on day 3 (0.66 x 10(9)/l (0.13-0.77)), and a decrease on day 5 ( 0.23 x 10(9)/l (0.06-1.23)) as compared with steady-state (0.40 x 10(9)/l ( 0.06-1.68)). The proportion of primitive BM hematopoietic progenitor cells (CD34(+)CD38(-), CD34(+)HLA-DR-, CD34(+)CD117(-)) decreased during G-CSF ad ministration, In parallel, a significant increase in the total number of CD 34(+) cells in peripheral blood was observed, achieving the maximum value o n day 5, These results suggest that in normal subjects the administration o f G-CSF for 5 days may reduce the number of progenitor cells in BM, particu larly the most primitive ones.