Factors affecting the efficiency of peripheral blood stem cell collection in children treated with chemotherapy and G-CSF

This retrospective study attempts to clarify the optimal timing for peripheral blood stem cell (PBSC) collection after conventional chemotherapy followed by granulocyte-colony stimulating factor (G-CSF) administration. Leukapheresis was performed 32 times in nine children with various cancers during bone marrow recovery phase following transient pancytopenia after chemotherapy. (On two occasions, leukapheresis was excluded because many leukemic blasts were included.) When the number of white blood cells (WBC) exceeded 1.8 times 10¹⁰/L after administration of G-CSF (200 μg/m², continuous infusion), many more CD34⁺ cells were contained in the collected peripheral mononuclear cells (P > 0.02) and a sufficient number of PBSC for transplantation (≥ 10 times 10⁸ CD34⁺ cells/kg) was obtained after one run in 15 of 17 leukapheresis sessions. In contrast, sufficient PBSC were obtained only in one of 13 runs of leukapheresis when the number of WBC was < 1.8 times 10¹⁰/L. The number of WBC on the day when PBSC were collected correlated with collected nuclear cell number (r = 0.60), but not with the CD34⁺ cell ratio. The ratio was higher only when both platelets and reticulocytes increased in parallel with WBC. We conclude that sufficient PBSC collection is possible after conventional chemotherapy using G-CSF, when hematopoietic recovery is parallel, without the use of high-dose chemotherapy.