The future of cytokine combination therapy

The hematopoietic growth factors including colony-stimulating factors (CSF) and interleukins (IL) have overlapping and pleiotropic effects on proliferation and differentiation of progenitor cells and stem cells. The regulatory signals can influence terminal differentiation and the cell cycle status, self-renewal, and differentiation of early pluripotential stem cells. Synergistic interactions between CSF and IL have been shown, both in vitro and in vivo, to be critical in hematopoietic regulation. The future of clinical trials of cytokines in congenital and acquired myelosuppressed states lies in the selective use of appropriate combinations of these regulatory macromolecules.