Action of the colony-stimulating factor, CSF-1

Area of Science:

• Hematology
• Cell Biology
• Immunology

Background:

• Colony-stimulating factor 1 (CSF-1) is a glycoprotein growth factor crucial for mononuclear phagocyte survival, proliferation, and differentiation.
• CSF-1 exerts its effects through a specific cell surface receptor found on these cells.
• The purified CSF-1 receptor is a 165,000 Mr glycosylated polypeptide that undergoes CSF-1-dependent tyrosine autophosphorylation.

Purpose of the Study:

• To investigate the role of CSF-1 and its receptor in the differentiation of mononuclear phagocytes.
• To identify early indicators of commitment to the mononuclear phagocytic lineage.

Main Methods:

• Characterization of the CSF-1 receptor.
• Analysis of CSF-1's effects on hematopoietic precursors in the presence and absence of other growth factors.
• Monitoring CSF-1 receptor expression levels during cell differentiation.

Main Results:

• CSF-1 alone supports the differentiation of mononuclear phagocytes from committed precursors (CFU-C) to macrophages.
• In conjunction with haemopoietin-1, CSF-1 can stimulate earlier precursors to differentiate into macrophages.
• A developmentally regulated increase in CSF-1 receptor levels on CFU-C precedes their differentiation into adherent, proliferating mononuclear phagocytes.

Conclusions:

• The increase in CSF-1 receptor expression is an early and reliable indicator of cell determination to the mononuclear phagocytic lineage.
• CSF-1 signaling is critical throughout the differentiation pathway of mononuclear phagocytes.