Description
SDF-1-alpha and SDF-1-beta are small cytokines belonging to the CXC-Chemokines. SDF-1 is identical with a chemokine reported to function as a pre-B-cell growth factor in the presence of IL-7 and isolated originally from a murine bone marrow stromal cell line. Human SDF-1-alpha and SDF-1-beta are encoded by a single gene and arise by alternative splicing. SDF-1 acts on lymphocytes and monocytes but not neutrophils in vitro and is a highly potent chemoattractant for mononuclear cells in vivo. In addition. SDF-1 also induces intracellular actin polymerization in lymphocytes. SDF acts as a chemoattractant for human hematopoietic progenitor cells expressing CD34 giving rise to mixed types of progenitors, and more primitive types. The chemotactic response is inhibited by pertussis toxin. Chemotaxis of CD34(+) cells in response to SDF is increased by IL-3 in vitro. SDF has been shown also to induce a transient elevation of cytoplasmic calcium in these cells