Mannan-binding protein in human umbilical cord blood.

Mannan binding protein (MBP) may be important for host defence particularly in infancy. MBP concentration was measured in 237 umbilical cord blood samples from singleton pregnancies and compared to those of 352 blood donors. Both data sets yielded a bimodal frequency distribution, consisting of a log-normal peak and a long tail of lower values. The range (0-23 U/ml) and median (7.2 U/ml) of cord blood values were significantly lower than those of blood donors (range 0-43 U/ml; median 8.3 U/ml). MBP was also measured in the cord blood samples of 8 pairs of twin siblings. Discordant values in two pairs of twins suggest that cord blood MBP is derived from the fetoplacental unit and not from the maternal circulation by transplacental passage.