On Feb. 22, 1991, the Food and Drug Administration (FDA) announced that it had approved Amgen’s two white blood cell colony-stimulating factors (G-CSF- NEUPOGEN) and (GM-CSF) for the treatment of congenital and acquired neutropenias and for mobilization of peripheral hematopoietic progenitor cells for stem cell transplantation.

Neutropenia refers to lower-than-normal levels of neutrophils in your blood. A neutrophil is a type of white blood cell that your bone marrow primarily makes. White blood cells in general, and neutrophils in particular, fight infections in your body.