GRANULOCYTE-COLONY-STIMULATING FACTOR DOES NOT ENHANCE PHAGOCYTOSIS OR MICROBICIDAL ACTIVITY OF HUMAN MATURE POLYMORPHONUCLEAR NEUTROPHILS IN-VITRO

The direct effects of human granulocyte colony-stimulating factor (hG- CSF) on mature polymorphonuclear neutrophils (PMNs) in vitro were stud ied with regard to chemotaxis, superoxide production, and phagocytosis and microbicidal activity against the following viable microorganisms : Staphylococcus aureus, serum-resistant Pseudomonas aeruginosa, and C andida albicans. Recombinant hG-CSF (rhG-CSF) acted as a chemoattracta nt for human PMNs in a dose-dependent manner. The chemotactic response of PMNs to N-formyl-methionyl-leucyl-phenylalanine (FMLP) was not enh anced by rhG-CSF at any of the concentrations used. rhG-CSF did not in duce the generation of superoxide by itself. However, rhG-CSF,vas able to prime human PMNs and to enhance O-2(-) release stimulated by FMLP in a dose-dependent manner. rhG-CSF did not enhance phagocytosis or ki lling of the three species of microorganisms by normal PMNs. With PMNs obtained from patients who had hematological disorders or solid tumor s, no enhancement of the microbicidal activity was observed in most ca ses. Microbial killing mediated by PMNs depended on the ratio of PMNs to target organisms. We concluded from these facts that the most impor tant effect of rhG-CSF was to increase the number of the peripheral PM Ns and not to enhance the functions of mature PMNs.