Abstract
Continuous intraperitoneal infusion of a macrophage colony-stimulating factor (M-CSF or CSF-1) for 6 d resulted in a 2.3-fold increase in the frequency of progenitor cells (CFUc) of macrophages in femoral marrow in C3H/HeN mice but there was no significant increase in the number of blood leukocytes in these animals. Infusion of bacterial lipopolysaccharide (LPS) also increased femoral macrophage CFUc frequency to the same extent as the above. Furthermore, the effect of the M-CSF preparation was much less pronounced in LPS-resistant C3H/HeJ mice than in LPS-sensitive C3H/HeN mice. The results show that the effect of M-CSF on bone marrow CFUc is marginal, even when it is administered in large amounts in the animals.
