Lymphokines: Enhancement by Granulocyte-Macrophage and Granulocyte Colony-Stimulating Factors of Neonatal Myeloid Kinetics and Functional Activation of Polymorphonuclear Leukocytes

Colony-stimulating factors, such as the granulocyte-macrophage and the granulocyte colony-stimulating factors (GM-CSF and G-CSF), are glycoproteins with biologic speci-ficity defined by their ability to support proliferation and differentiation of hematopoi-etic cells of various lineages. Their physiologic activities include stimulation and prolifer-ation of early stem cell precursors and functional activation of mature peripheral effector cells. Recently produced recombinant human (rh) GM-CSF and G-CSF have been demon-strated to regulate hematopoietic neutrophil progenitor colony growth; to stimulate the release of bone marrow neutrophil storage pools; and to prime mature effector functions, including chemotaxis, oxidative metabolism, phagocytosis, C3bi receptor expression, and antibody-dependent cytotoxicity in adults. We examined the effects of rh-GM-CSF on priming superoxide release and chemotaxis of neonatal (cord) polymorphonuclear leu-kocytes (PMNs) and of rh-G-CSF and rh-GM-CSF on bone marrow neutrophil egress in the neonatal rat. A time-response evaluation of the effect of rh-GM-CSF revealed enhanced release of superoxide by PMNs. PMN chemotaxis also was enhanced by rh-GM-CSF, with a maximal response occurring earlier than enhanced superoxide release