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Immunomediators seem to have a central role in the immune system of both human milk and newborn infants. CD31/PECAM-1 is an adhesion molecule, member of Ig gene superfamily, mediating cell–cell adhesion in both homophilic and heterophilic ways. Levels of the soluble form of PECAM-1 (sPECAM-1) were evaluated on the 2nd and 5th day postpartum in breast milk and serum paired samples from 20 lactating women as well as in time-matched serum from their single, term, healthy neonates. Concentrations of sPECAM-1 in breast milk (median, range) on both the 2nd (2.05 ng/ml, 0.0–7.2) and 5th day postpartum (0.89 ng/ml, 0.0–3.6) were about 10 and 20 times lower than those (mean±SD) in controls (healthy adults) (19.83±5.17, p<7×10−8), showing a significant fall from the 2nd to the 5th day postpartum (p<0.0005). Maternal serum sPECAM-1 values (mean±SD) were significantly lower on the 2nd day postpartum (14.21±5.15 ng/ml) than those in controls (p<0.002), but reached control values on the 5th day postpartum after a significant rise (p<0.0075). Neonatal serum sPECAM-1 values with no significant difference between the 2nd (14.4±4.11 ng/ml) and 5th day of life (14.54±4.99 ng/ml) were significantly lower than those in controls (p<0.002). Values of sPECAM-1 in milk and sera of lactating mothers and their neonates on the 2nd day postpartum depended on the mode of delivery, being significantly lower after caesarean section (p<0.034, p<0.0075 and p<0.035, respectively). In conclusion, our findings in the early postpartum period demonstrate that: (a) sPECAM-1 is present in human milk in low and decreasing concentrations; (b) the shedding of sPECAM-1 is an established component of the neonatal immune system from birth, though in lower concentrations than in adults, possibly reflecting its immaturity; and (c) the mode of delivery has a significant effect on sPECAM-1 values in milk and sera of lactating mothers and their neonates; the lower values after caesarean section may reveal a deranged endothelial homeostasis. [Copyright &y& Elsevier]

In breast milk and paired serum from 70 lactating women and 40 of their term, infection-free neonates, on the 2nd and 5th day postpartum slCAM-1, sVCAM-1, sE- and sL-selectin were measured by ELISA and compared with those in 26 healthy adults (controls). Seven infant formulas and fresh milk from five cows were also analyzed. Human colostrum values of slCAM-1, sVCAM-1 (similar to those in maternal and control serum), sE-selectin and sL-selectin (~10 and ~100 times lower than in maternal and control serum) were significantly higher than those in milk, while they varied widely. None of the adhesion molecules was detected in fresh cow's milk or infant formulas. Exclusively breast-fed infants showed significantly higher values of slCAM-1 and sL-selectin on the 2nd day of life than those supplemented also with formula. Only slCAM-1 values correlated positively between colostrum and time-matched maternal serum. These findings show in human milk important amounts of slCAM-1 and sVCAM-1 but minimal amounts of sE- and sL-selectin, which could affect the immune system of the neonate. [ABSTRACT FROM AUTHOR]