Alterations in the Umbilical Cord Blood NK Cells Related to the Mode and the Time of Delivery.

Natural killer (NK) cells take part in the early immunological response to infection. Their lower cytotoxic activity in the neonates, especially premature ones, compared to children and adults, is assumed to be one of the factors responsible for high susceptibility to infections. Moreover, alterations in every components of immune response during anesthesia and surgery have been suggested. The numbers of natural killer cells are decreased postoperatively. The aim of the study was to estimate the influence of the mode and time of delivery on the number of leukocytes, number and percentage of lymphocytes and natural killer (NK) cells. The NK cells were examined by the three-color flow cytometry with the use of monoclonal antibodies of Becton Dickinson in the following study groups: (1) full-term neonates born by normal spontaneous vaginal delivery (n=19); (2) preterm neonates born by normal spontaneous vaginal delivery (n=15); (3) full-term neonates born by elective cesarean section under epidural anesthesia (n=23); (4) preterm neonates born by cesarean section under epidural anesthesia (n=22). The number of leukocytes was similar in all examined neonates. The numbers of leukocytes were lower albeit not significantly in preterm neonates born by cesarean section. The numbers of lymphocytes were also similar in all examined neonates but the percentage of lymphocytes was higher in the preterm neonates than in the full-term ones (p<0,05). The number and percentage of natural killer (NK) cells were higher in the neonates born by normal spontaneous vaginal delivery both full-term and preterm ones. The significant lowest value of NK cells was in the preterm neonates born by cesarean section under epidural anesthesia. These results suggest that either mode of delivery or time of delivery might influence the NK cell numbers in the umbilical cord blood of the neonates.