Granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) are glycosylated polypeptides that induce an increase in the proliferation and maturation of white blood cells including neutrophils and monocytes-macrophages. Recombinant forms of these colony stimulating factors are used to treat severe neutropenia in patients receiving cancer chemotherapy or undergoing hematopoietic cell transplantation. Recombinant forms include filgrastim (G-CSF) and sargramostim (GM-CSF), both of which are commercially available for therapy of severe neutropenia and bone marrow failure. Neither filgrastim nor sargramostim have been linked to serum enzyme elevations during therapy or to clinically apparent liver injury.