Polymorphonuclear leukocyte function in the preterm neonate: effect of chronologic age

In this study, effect of chronologic age on polymorphonuclear leukocyte (PMN) chemiluminescence and random and chemotactic motility was evaluated in 38 stable preterm neonates of less than 32 weeks' gestation during the first month of life. Chemiluminescence and random and chemotactic motility of PMNs from preterm neonates were first evaluated at mean postnatal age of 9.8 days and then weekly for an ensuing 21-day period. For comparison, one blood sample was obtained for PMN functions from 14 healthy term neonates younger than 72 hours of age and seven normal adults. On day 1 PMN chemiluminescence and random and chemotactic motility values in preterm neonates were significantly lower (P less than .001) compared with those in term neonates and PMN function values of term neonates were significantly lower (P less than .001) than those of adults. Although initial PMN chemiluminescence and random and chemotactic motility values in preterm neonates were depressed, subsequent values on days 7, 14, and 21 increased significantly (P less than .002). On day 21 (mean postnatal age of 30.8 days) no differences existed in chemiluminescent activity and random motility between preterm and term neonates; chemotactic motility in preterm neonates, however, remained impaired. Mean cumulative age (gestational age at birth plus postnatal age) of preterm neonates on day 21 of study was 32.5 weeks, suggesting that chronologic age has more effect on maturational changes in PMN functions than gestational age.