THE COLONY-STIMULATING FACTORS

Hematopoiesis is a dynamic process, which generate in the range of 10( 9) cells/kg each day of erythroid and myeloid cells respectively. In v itro assays that were developed 20 years ago, have been used to define factors that can stimulate growth and differentiation of bone marrow (BM) derived progenitor cells. These growth factors for hematopoiesis were termed Colony Stimulating Factors (CSFs) since the assay system w as to induce colonies. With the application of molecular biologic appr oaches, the genes encoding for these CSFs have been localized and clon ed. Production of CSFs and other soluble signal substances (cytokines) as pure proteins have led to important insights into how hematopoiesi s is regulated by a complex network made up by interactions between ce lls and cytokines. The availability of CSFs in clinically useful amoun ts has also led to clinical trials with new strategies for treating he matopoietic dysfunctions, congenital or acquired. Because others have recently reviewed clinical applications or basic science studies on th e colony stimulating factors, we will summarize the two with focus on common features between the different CSFs.