The effect of serum containing granulocytic stimulating activity and colony stimulating activity on regenerating hemopoiesis in mice.

The influence of postinflammatory rat serum containing granulocytic stimulating activity (GSA) on the process of spontaneous regeneration of hemopoietic tissue was studied and compared to the effect of colony stimulating activity (CSA) in CBA mice in the regenerative phase of hemopoiesis after aplasia induced by a sublethal dose of cyclophosphamide (Cy). One hour after Cy application, mice were injected with 0.2 ml of GSA or CSA. Then 6, 12, 24 and 48 hr later the changes within bone marrow and spleen CFU - GM, morphologically recognizable hemopoietic cells and white blood cells (WBC) were followed. GSA stimulated spontaneous regeneration of granulocytic cells, specifically increasing the number of morphologically recognizable proliferative granulocytes continuously during 48 hr. The number of bone marrow (at the 6th hr) and splenic (until the 24th hr) CFU - GM were also increased under the influence of GSA. Under the same experimental conditions in vivo, CSA did not induce any changes within bone marrow granulocytic cells, but the increase in splenic CFU - GM was observed until the 12th hr. The differences in the action of GSA and CSA on the process of spontaneous regeneration of granulocytic cells in vivo in Cy treated mice indicate that these 2 factors play different roles in the regulation of granulopoiesis.