Effects of cyclophosphamide on murine bone marrow and splenic megakaryocyte-CFC, granulocyte-macrophage-CFC, and peripheral blood cell levels.
The effect of cyclophosphamide (CY) on megakaryocytopoiesis in mice was examined with assays of megakaryocyte colony-forming cells (Meg-CFC) in bone marrow and spleen and simultaneous determinations of peripheral blood counts, after a single intraperitoneal dose (200 mg/kg) of CY. Significant rebound thrombocytosis (170% of normal) occurred at day 11 after injection with CY, although only modest preceding thrombocytopenia (70% of normal) was observed. After an initial 3-5 day period of suppression, total megakaryocyte colony-forming cells (Meg-CFC) in both bone marrow and spleen of CY-treated mice demonstrated rebound increases at 5 and 7 days, respectively, after administration of the drug. Granulocyte-macrophage colony-forming cells (GM-CFC) exhibited alterations which were similar to those of Meg-CFC, suggesting similar sensitivities of Meg-CFC and GM-CFC to CY. The increase in Meg-CFC in both bone marrow and spleen preceded development of thrombocytosis by 4-6 days. This suggests that increased platelet counts in CY-treated mice are attributable, at least in part, to alterations in feedback mechanisms which control megakaryocytopoiesis, with resultant stimulation of the megakaryocyte progenitor compartment.
D000818:Animals; D003520:Cyclophosphamide / Q000494:pharmacology*; D006098:Granulocytes / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D010976:Platelet Count; D013154:Spleen / Q000166:cytology; D013922:Thrombocytosis; D013997:Time Factors
D003520:Cyclophosphamide