Effect of serum from leukapheresed mice on myelocytes, promyelocytes and colony-forming cells.

Leukapheresis of neutrophil granulocytes in mice increased the myelopoietic activity of their serum. Leukapheresed mouse serum (LMS) caused a threefold increase in the in vitro stathmokinetic index of myeloid precursors. Five to ten minutes of incubation were sufficient to change the colony-forming capacity of mouse bone marrow cells as expressed by the increase in the ratio of granuloid to erythroid cells in spleen colonies. The in vitro stathmokinetic index assay also showed that there are diurnal variations in levels of granulopoietic activity in normal mouse sera. However, at any time of the day, LMS had higher granulopoietic activity.