SOLUBLE L-SELECTIN (SCD62L) UMBILICAL-CORD PLASMA-LEVELS INCREASE WITH GESTATIONAL-AGE

L-Selectin (CD62L) is a leukocyte surface membrane glycoprotein involv ed in extravasation and homotypic aggregation which is rapidly cleaved off after cellular activation. From culture supernatants and body flu ids, soluble L-selectin (sCD62L) has been recovered with its functiona l activity retained. We devised a sensitive enzyme-linked immunoassay for quantitation of sCD62L which was used to measure sCD62L in umbilic al cord plasma of 255 human newborns with a gestational age (GA) of 23 -43 wk (median 38 wk). sCD62L levels ranged from 1.14-13.8 pmol/mL (me dian 7.2 pmol/mL) and showed strong correlations with GA (r = 0,71, p < 0.001), birth weight (r = 0.66, p < 0.001), and absolute neutrophil cell counts (ANC) (r = 0.62, p < 0.001) obtained from a peripheral vei n within the first 6 h of life (n = 153), whereas there was a weak inv erse correlation with absolute normoblast counts (r = -0.27, p < 0.001 ). In multiple regression analysis, only GA and ANC retained a signifi cant association with sCD62L levels (p < 0.001). Decreased sCD62L leve ls were found to be associated with multiple gestation (4.8 +/- 2.4 pm ol/mL versus 7.7 +/- 2.3 pmol/L, p < 0.05) also when considering GA an d ANC as covariates. In contrast, increased sCD62L levels in infants b orn from meconium-stained amniotic fluid, and decreased levels in newb orns with acute bacterial infection could be fully attributed to diffe rences in GA and ANC. Umbilical cord blood sCD62L levels of healthy, t erm, vaginally born singletons (n = 38) were significantly lower (8.5 +/- 2.2 versus 11.8 +/- 1.9, p < 0.0001) than cubital vein levels of h ealthy adults (n = 20). We conclude that sCD62L levels display a stron g increase during fetal maturation.