Abstract
Summary
The spleen colony system was used to test in vivo effects of hemopoietins on the total and differential exocolonizing potential of A/J mouse marrow colony-forming units (CFU) transplanted serially into primary and secondary, supralethally irradiated, isogeneic hosts. The hemopoietins used were GPF (calf renal granulopoietic factor) and ESF (erythrocyte stimulating factor-rich anemic horse plasma).
As measured by total and differential primary host spleen colony counts, GPF and ESF evoked a time-dependent increase in a pool of committed donor CFU. These CFU were transplantable from primary into secondary hosts without losing their hemopoietininitiated, cell line-specific commitment.
The f-fraction remained within normal limits (0.112-0.125) in all experimental groups when primary host spleen cells were harvested at 24 hr and transplanted into secondary hosts. When the donor CFU were allowed to reside and replicate in the primary host spleen for 8 days before retransplantation into the secondary hosts, the f-fraction manifested a 27-29-fold increase for salineand ESF-treated marrow-derived CFU, but only an 19-fold increase for GPF-treated marrow-derived CFU. Theoretical explanations for this difference in CFU seeding efficiency are discussed.
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