Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) induces proliferation and differentiation of hematopoietic stem cells. Additionally, rhGM-CSF enhances the physiologic responses of adult polymorphonuclear leukocytes (PMN) especially with respect to oxidative metabolism and chemotaxis. Neonatal PMN are deficient in chemotaxis and have been demonstrated to have reduced oxidative responses in times of stress. We evaluated the priming effects of rhGM-CSF (1-100 pmol/L) on cord (neonatal) superoxide production and chemotaxis. Cord and adult PMN were incubated with 100 pmol/L rhGM-CSF (Amgen, 4 x 10(7) U/mg) for 0-120 min and stimulated with N-formyl-l-methionyl-l-leucyl-phenylalanine. RhGM-CSF enhanced O2- production at all time periods with maximal priming at 60 min (147.97 +/- 11.14% p less than or equal to 0.006) with less, but significant enhancement at 120 min (116.53 +/- 7.92% p less than or equal to 0.05). Maximal adult PMN O2- release occurred at 120 min (190.02 +/- 8.71% p less than or equal to 0.003) and was more pronounced than cord PMN.(ABSTRACT TRUNCATED AT 250 WORDS)