Effect of maternal labor and mode of delivery on neutrophil actin response to N-formylmethionyl-leucyl-phenylalanine in healthy neonates.

Diminished actin response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) has been used to explain the impaired chemotaxis of neonatal neutrophils, but the effect of labor on this response has not been evaluated before. Therefore, we tested the hypothesis that labor stress may have an effect on actin response of cord blood neutrophils to FMLP. This response is compared by phallacidin stain of neutrophil F-actin and flow cytometry analysis among 3 groups of healthy neonates: group I, 16 vaginally delivered neonates; group II, 16 neonates delivered by elective cesarean section without labor; and group III, 16 neonates delivered by cesarean section after labor. In the group III, 10 infants were delivered by an emergency cesarean section because of fetal heart rate deceleration indicating fetal distress (one minute Apgar score < 7 in 5 cases [50%]), and the other 6 infants were delivered because of failure of progression of labor (one minute Apgar score < 7 in 2 cases [33.3%]). Stimulated relative F-actin content of neutrophils in group III was increased compared with groups I and II. There was no such difference between neutrophils from infants of groups I and II. The results of this study indicate that fetal distress may enhance neutrophil actin response to FMLP, while labor or mode of delivery might not have such effect.