Effects of N-linked Carbohydrate on the In Vivo Properties of Human GM-CSF

The hematopoietic system provides a unique opportunity for the development of useful protein pharmaceuticals. In this system, hematopoietic progenitor cells found in the bone marrow continuously divide and differentiate, ultimately resulting in the release of mature blood cells into the periphery. A number of different polypeptide growth factors have been identified that are capable, at least in vitro, of regulating the production of mature blood cells (for review, see Metcalf 1984). In principle, any of these growth factors could prove valuable in the treatment of cytopenias, both naturally arising and those induced by chemotherapy or irradiation therapy for cancer (Gasson et al. 1983). These proteins are particularly attractive as therapeutic agents because their target cells in the bone marrow are readily accessible to soluble drugs via the circulatory system.