Natural killer cell subsets and function in newborns

Objective The aim of this study was to explore the subsets and function of natural killer cells from neonatal umbilical cord blood. Methods umbilicus cord blood of neonates who were born to HBV DNA negative(<500copies/ml) mothers were collected; peripheral blood of healthy adults were collected as control group.Flow cytometry was employed to detect the frequency of NK cells and pDC, the expression of pDC surface molecules CD80, CD83, CD86 were detected at the same time.Detection technology of Luminex was used to detect the level of IFN-r, IFN-a, IL-10, IL-6 in whole blood of two groups inspectively, and FlowJo software was used to analyse these indicators among two groups.Two groups of samples were compared with Mann-Whitney test and t test. Results 24 umbilicus cord blood of neonates and 6 peripheral blood of healthy adults were collected.In cord blood, the frequency of CD16+ CD56+ NK and the positive rate of CD16+ CD56dim NK cells were significantly lower than these indicators in control group (19.36±11.41, 44.30±9.79, P= 0.000), however the positive rate of CD16-CD56bright NK cells have no significant difference between the two groups.The frequency of pDC and the positive rate of pDC surface molecules CD80, CD83, CD86 were significantly lower(P=0.000). The level of IFN-r was significantly lower(P=0.003), but IFN-a, IL-6 and IL-10 had no difference among these two different groups. Conculsions The reduced frequency of NK and pDC may be involved in the possible mechanism which lead to low antiviral immune ability of newborns. Key words: Killer cells, natural; Dendritic cells; Cytokines; Infant, newborm; Newborn; Hepatitis B virus