Macrophage-colony stimulating factor is required for the production of neutrophil-promoting activity by mouse embryo fibroblasts deficient in G-CSF and GM-CSF

Abstract

G-CSF and GM-CSF play important roles in regulating neutrophil production, survival, differentiation, and function. However, we have shown previously that G-CSF/GM-CSF double-deficient [knockout (KO)] mice still develop a profound neutrophilia in bone marrow and blood after infection with Candida albicans. This finding suggests the existence of other systems, which can regulate emergency neutrophil production. We have now developed an "in vitro" technique to detect and characterize a neutrophil-promoting activity (NPA) in the media conditioned by mouse embryonic fibroblasts (MEFs) derived from G-CSF-/-/GM-CSF-/- mice. NPA is produced in vitro by the MEFs after stimulation with LPS or heat-in..