T cell activation in abnormal perinatal events

The aim of this study was to determine the percentage of CD45RO⁺ T cells in umbilical cord blood from neonates born at less than 37 weeks of gestation. Fifty-nine patients were enrolled in this study, including 49 with preterm and 10 with term deliveries. Preterm deliveries were divided into two categories; spontaneous (Group A, n = 31) and indicated (Group B, n = 18). Perinatal infection was categorized as C-CAM, H-CAM and neonatal infection. The percentage of CD45RO⁺ T cells in the umbilical cord was assessed using flow cytometry. IL-6 was measured using ELISA. In Group A, the percentage of CD45RO⁺ T cells and concentrations of IL-6 in patients with perinatal infection ( n = 18) were significantly higher than in those without perinatal infection ( n = 13). A significant correlation between percentage of CD45RO⁺ T cells and IL-6 concentrations was observed in the cord blood ( r = 0.62, P = 0.001). In Group B, pink–tinged amniotic fluid was observed in seven cases. In these cases, an increase in the percentage of CD45RO⁺ T cells (>10%) was noted. In the cases without perinatal infection, which included all those delivered at term ( n = 32), no correlation was observed between the percentage of CD45RO⁺ T cells and gestational age at delivery ( r =?0.139, P = 0.448). We concluded that a high percentage of CD45RO⁺ cord blood T cells is observed not only in perinatal infection, but also in the presence of abnormal perinatal events such as maternal bleeding in preterm gestation.