Decreased Phytohemagglutinin-Induced Aggregation and C5a-Induced Chemotaxis of Human Newborn Neutrophils

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Abstract
Summary: Phytohemagglutinin (PHA)-induced lectin aggregation, chemotactic response to C5a, and random migration were measured on paired samples of neutrophils obtained from human peripheral blood and cord blood of normal newborn infants. The mean aggregation rate (± 1 SD) of adult neutrophils with PHA was 16.8 ± 4.4 vs. 12.0 ± 3.6 for newborn neutrophils (P < 0.005), and the mean percent aggregation of adult neutrophils was 56.2 ± 9.2 vs. 45.6 ± 8.3 for newborn neutrophils (P < 0.005). Exposure to newborn plasma had no affect on adult neutrophil aggregation. Whereas vinblastine (VBL) decreased both the percent and rate of PHA-induced adult neutrophil aggregation, only the rate of newborn neutrophil aggregation was reduced by VBL. Newborn neutrophil chemotactic response to C5a, was reduced by 80% (P < 0.0025), and showed a positive correlation with percent PHA-induced aggregation (r = 0.6037, P < 0.05). On the other hand, random migration was not significantly reduced and did not correlate with PHA-induced aggregation. These observations suggest that the decreased chemotactic responsiveness of newborn neutrophils may be due to developmental membrane differences which adversely affect the number and/or availability of C5a receptors. Lectin-induced aggregation studies of other chemotactic defects may identify similar differences. Speculation: Although the precise nature of decreased newborn neutrophil chemotactic responsiveness remains unknown, these studies demonstrating decreased PHA-induced aggregation and decreased chemotactic response of newborn neutrophils suggest that developmental membrane differences in newborn neutrophil may adversely affect requisite premigratory membrane events. Persistence of these developmental membrane differences or their reappearance may be the basis of other chemotactic defects.

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