Reduced response to granulocyte colony-stimulating factor in W/Wv and Sl/Sld mice.

The response of W/Wv and Sl/Sld mice to recombinant granulocyte colony-stimulating factor (rG-CSF) was investigated. Purified rG-CSF was injected every day for 1 week in doses up to 1000 micrograms/kg. Both untreated Sl/Sld and W/Wv mice initially showed an ordinary number of neutrophils and then an increase in neutrophils in response to rG-CSF injections. However, the effective dose of rG-CSF was much higher than that for normal mice. An increase in splenic CFU-GM was observed in both types of mice receiving 1000 micrograms/kg of rG-CSF, regardless of the reported defects in their hemopoietic system. These results indicate that W/Wv and Sl/Sld mice show a reduced response to exogenous rG-CSF and that a large amount of exogenous rG-CSF may allow an increase in neutrophils in certain hemopoietic defects.