Stimulation of granulopoiesis by androgens without concomitant increase in the serum level of colony stimulating factor.

The marked enhancing effect of daily injections of 19-nortestosterone decanoate (19-ND) upon granulopoietic recovery of mice made neutropenic by a single dose of BCNU was studeid in regard to the possible regulatory role of CSF. Serum levels of CSF in BCNU-treated mice with or without 19-ND injection were not found to differ significantly from those in normal mice. BCNU treatment with or without 19-ND did not alter the CSF increases in response to endotoxin injection. Increases in dividing marrow granulocytes in the 19-ND mice were preceded by increases in their marrow CFC. The acceleration of granulopoietic regeneration was thus not mediated by the serum colony stimulating factor. It is attributed to a stimulatory effect of 19-ND on proliferation of CFC and/or CFU.