Quantification of the peripheral blood colony forming unit-culture rise following chemotherapy. Could leukocytaphereses replace bone marrow for autologous transplantation?

Because hematopoietic stem cells circulate in the peripheral blood (PB), the possibility exists for using leukocytaphereses in place of marrow for autologous transplantation. Normal stem cells, measured by the colony forming unit-culture (CFU-C) assay, usually in extremely small numbers in PB, are increased after aggressive chemotherapy. Patients with small-cell undifferentiated carcinoma of the lung had PB assayed for CFU-C numbers during induction chemotherapy. The median blood CFU-C concentration increased as much as 13.3-fold compared to pretreatment values following the third cycle of chemotherapy. The CFU-C peaks occurred at the same time as a relative monocytosis in the PB, with monocytosis percentages often 30 percent or higher. Compared to an average CFU-C dose obtained from a typical marrow procedure done under general anesthesia (4.0 X 10(4) CFU-C/kg), the anticipated CFU-C yield obtained from a single cytapheresis performed at the CFU-C peak after the third course of chemotherapy (2.9 X 10(4) CFU-C/kg) suggests that as few as two-cytaphereses could provide sufficient stem cells to reconstitute hematopoiesis following lethal myelosuppression.