NEONATAL NEUTROPHIL INFLAMMATORY RESPONSES - PARALLEL STUDIES OF LIGHT-SCATTERING, CELL POLARIZATION, CHEMOTAXIS, SUPEROXIDE RELEASE, AND BACTERICIDAL ACTIVITY

Neutrophil dysfunction among newborn infants, especially those born pr ematurely, Is well recognized, but the mechanism responsible for this phenomenon is yet to be clarified. In this study, we evaluated the sti mulus response coupling in neutrophils from 90 healthy newborns and 96 healthy adults in an effort to establish whether defective neonatal n eutrophil function is a result of impaired signal perception or immatu re responsiveness. Measurement of rapid-and slow-light scattering resp onses (LSR) to 1 mu M FMLP stimulation revealed that neonatal neutroph ils have about one-half the corresponding responsiveness of adult cell s (rapid-LSR: 6.1 +/- 3.1 arbitrary light intensity units vs. 12.0 +/- 2.8, P<.001; and slow-LSR: 5.0 +/- 2.5 vs. 9.1 +/- 2.0; P<.001). The same markedly reduced activity was observed in newborn neutrophil chem otaxis and bactericidal activity in comparison with adult cells. Never theless, low FMLP concentrations (less than 1 nM) induced no differenc e in cell polarization between newborn and adult neutrophils, yet at h igher FMLP concentrations, the newborn revealed significantly reduced cell polarization. Our data suggest that newborn infants bear a fully functional FMLP signal perception but lack the full capacity of inflam matory responsiveness. (C) 1998 Wiley-Liss, Inc.