TSK Wan, CY Yeung, AYC Tam

Preterm infants are more susceptible to serious infections than are term infants. Apparently, this is a manifestation of the functional immaturity of the defence mechanism. Many investigators have reported on the functions of the polymorphonuclear leukocytes of term infants, but information on the preterm newborn is scarce. We delineated the neutrophil functions in preterm and term neonates of Chinese origin. 286 Chinese neonates admitted to two major neonatal units of Hong Kong were randomly selected for the study. Candidacidal activity, phagocytosis, chemotaxis and nitroblue blue tetrazolium reduction (NBT) scores were evaluated from 2.5 ml peripheral blood of each infant. The chemotactic activity of the preterm neonates was significantly (P < 0.05) lower than that of the term infants. The candidacidal activity, phagocytosis and NBT scores of the two groups were, however, similar and these values were also similar to those of adult controls. The candidacidal activity of male babies was significantly (P < 0.05) lower than that of females. Our findings of similar candidacidal activity and phagocytosis of preterm and term Chinese infants contradict reports on Caucasians. They may explain our earlier observation of much reduced mortality of only 8.7% from early group B streptococcal infection in our infants, which is in sharp contrast to the 30-50% mortality rates reported from most American and European centres.