Impaired Leukotriene B, Release by Neonatal

and were significantly (t test, p < 0.01) lower in newborn than in adult samples (means 2 SD: 0.71 2 0.22 and 3.19 ? 1.06 ng/106 PMN, respectively). Finally, when the PMN were stimulated by formyl-methionyl-leucyl-phenylalanine, the release of LTB, was highly variable both in newborn and in adult samples, as previously reported. In conclusion, the PMN response to A23187 provides evidence that in neonatal PMN the lipoxygenase pathway for LTB, synthesis is already fully developed at birth. However, the neonatal cells were defective when triggered by a receptor-mediated stimulus, suggesting the presence of a limiting step in transmembrane signal transduction that results in a low response in neonatal PMN. (Pediah. Res 36: 60-63, 1994) Abbreviations LTB,, leukotriene B, PMN, polymorphonuclear leukocyte N-PMN, neonatal PMN A-PMN, adult PMN fMLP, formyl-methionyl-leucyl-phenylalanine STZ, human serum-treated zymosan HBSS, Hanks' balanced salt solution GC-MS, gas chromatography-mass spectrometry HETE, 12-hydroxyeicosatetraenoic acid