Granulocyte functions and changes in ability with age in newborns; Report no. 1: Flow cytometric analysis of granulocyte functions in whole blood

Background: Serious bacterial infections occur with higher frequency in the first weeks of life than in other age groups and this may be, in part, related to functional impairment of neonatal granulocytes. The purpose of the present study was to estimate the characteristics of granulocyte function during the neonatal period. Methods: The expression of adhesive molecules on the surface of granulocytes present in umbilical cord blood and peripheral blood obtained at 5 days and 1 month after birth, H2O2 production and protease activity in granulocytes were studied by comparison with adult blood. Results: Although there were no significant differences observed with respect to the expression of CD11b on the surface of granulocytes between each age group and adults, l-selectin was significantly lower in cord blood as compared with adult blood. Production of H2O2 by granulocytes was significantly lower for cord blood than peripheral blood from 1 month old infants or that from adults in the presence of either phorbol myristate acetate or N-formyl-methionyl-leucyl-phenylalanine stimulation. The intracellular activity of elastase and collagenase within granulocytes exhibited a higher tendency for cord blood as compared with adult blood. Conclusions: Decreased functions of part of the phagocyte system during early infancy were clearly observed.