Serum soluble E- and L-selectin in the very early neonatal period

Both E- and L-selectin are cell adhesion molecules. E-selectin is expressed by activated endothelial cells, whereas L-selectin by quiescent leukocytes and is rapidly cleaved off after activation. Both selectins take part in the first step of the 'adhesion cascade', the 'rolling of leukocytes', leading to the extravasation of the white cells to the sites of inflammation, infection or damage. For this reason their soluble forms (sE- and sL-selectin, respectively), are considered early and reliable markers of the immune activation and response. Moreover, sE-selectin has been reported to be a potent angiogenic factor and a reliable marker of infection and sepsis in neonates, as well as endothelial activation, while sL-selectin of the leukocyte function and maturity. Following informed maternal consent, we evaluated prospectively by ELISA, sE- and sL-selectin in the serum of 40 (19 females, 21 males), healthy, term, infection-free neonates, on the second and fifth day of life, and compared them with the respective values in 20 healthy adults (10 females, 10 males), with the purpose of examining the pattern of their values in the early postpartum days, and to establish reference values for both selectins. Values (mean+/-S.D.) of sE-selectin both on the second (139+/-48 ng/ml) and fifth day of life (111+/-35 ng/ml) were found to be highly increased, as compared with those in controls (48+/-13 ng/ml; P<4 x 10(-11) and P<4 x 10(-10), respectively), while sL-selectin values on both the second (674+/-223 ng/ml) and the fifth day of life (684+/-221 ng/ml), were significantly lower than those in controls (938+/-181 ng/ml); P<0.0001 and P<0.0003, respectively). A significant decrease was noted in sE-selectin values, from the second to the fifth day of life (P<10(-7)), while sL-selectin values showed no significant change in the same time interval. A strong correlation was found between values on the second and the fifth day of life of both sE- and sL-selectin (r(P)=0.885 and r(P)=0.813, respectively; P<0.00001). Neonatal values of both sE- and sL-selectin on the second or on the fifth day of life, did not depend on the perinatal factors, neonatal sex, or birth weight, mode of delivery, and maternal age or parity. In conclusion, in the very early neonatal period, our findings of highly increased sE-selectin, while low sL-selectin, suggest an immune and more specifically endothelial activation and an immature and decreased leukocyte function.