Superoxide production by neutrophils in children with malignant tumors treated with recombinant human granulocyte colony-stimulating factor

Background. Human recombinant granulocyte colony-stimulating factor (rhG-CSF), widely used to combat chemotherapy-induced neutropenia, stimulates both in vivo and in vitro intra- and extracellular O₂ ^- production in human polymorphonuclear cells (PMNs). Patients and Methods. Twelve patients with solid tumors or acute lymphoblastic leukemia were treated during induced aplasia with rhG-CSF (5 μg/kg/day). Intra- and extracellular O₂ ^- production by PMNs isolated from these patients after 5 days of rhG-CSF therapy was assessed following both fMLP and FMA stimulation. Results. All patients showed a rise in PMN count; administration of rhG-CSF enhanced intra- and extracellular O₂ ^- release after fMLP but not after PMA stimulation. Conclusions. rhG-CSF potentiates in vivo O₂ ^- production by PMNs stimulated with receptor-mediated agonists via G-protein (e.g. fMLP), but not by those stimulated with agonists that bypass receptors via protein kinase C (e.g. PMA).