HUMAN CORD AND NEWBORN BLOOD IS DECREASED IN NATURAL KILLER CELL CYTOTOXICITY IN COMPARISON WITH NORMAL ADULT

Abstract

Because natural killer cell cytotoxicity (NKC) is implicated in transplant rejection and we are involved in neonatal cardiac transplantation, it is important to understand normal NKC in neonates. We studied NKC in cord and newborn (2-4 days) blood from full term normal spontaneous vaginal delivery (FTNSVD) n=40, full term cesarean section (FTC/S) n=34, preterm normal spontaneous vaginal delivery(PTNSVD) n=18 and preterm cesarean section (PTC/S) n=14, and compared these with normal adult blood (NA), X=30,(22-42 yrs). NKC was measured by a standard 4 hr 51-Cr release assay using K562 as target cells. The Student's t-test was used to determine differences in NKC. The results at the 50:1 ratio were significantly different, p<0.01, between NA and both cord and newborn blood in all four groups. The slopes of the response curves for all these groups were also significantly different from NA, p<0.01. Preterm categories for cord NSVD and newborn C/S were significantly lower than their respective full term category, p<0.01. In addition, there was no significant difference between NSVD and C/S for all groups. In conclusion, cord and newborn blood in all groups studied were found to have significantly lower NKC than that of NA blood. These data provide a better understanding of normal NKC maturation in the neonate relative to transplantation and immunosuppression.