The role of CSF in the production of activated phagocytes during infection is summarized in Figure 2. Resident macrophages and immigrating granulocytes serve in the first line of host defenses against microbial invasion. The phagocytes kill some of the invading microorganisms and the macrophages process and present microbial antigens to antigen-specific T lymphocytes. IL-1 secreted by a number of cell types, including macrophages, promotes clonal expansion and the activation of sensitized T lymphocytes, which in turn produce a variety of cytokines, including CSF. These cytokines, in combination with the microbial products released during infection, stimulate the proliferation and differentiation of bone marrow progenitor cells and the increased formation of circulating white blood cells. In response to chemotactic factors, the phagocytes in the circulation adhere to endothelial cells adjacent to the inflammatory site, undergo diapedesis, and migrate to the site of infection. These phagocytes, activated by CSF and other cytokines, exhibit increased antimicrobial activity. Thus, the CSF play a central role in phagocyte production, differentiation, and activation. The genes encoding the CSF in humans and in mice have been cloned and expressed as recombinant material. The recombinant CSF exhibit essentially the same biological activity as do the native proteins. Moreover, many of the activities expressed in vitro have also been observed in vivo. The results of animal experiments and clinical trials confirm the role of CSF in phagocyte production and the augmentation of host defenses. While cytokines are currently being evaluated on an individual basis, therapies in the future may involve a combination of cytokines used in an effort to control host defenses precisely and to provide more effective treatment. It has been shown, for example, that murine IL-3 and M-CSF induce the cycling of progenitor cells when used together at doses that are individually ineffective (148).
|Original language||English (US)|
|Number of pages||12|
|Journal||Proceedings of the Society for Experimental Biology and Medicine|
|State||Published - Sep 1991|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)