PLACENTAL ALKALINE-PHOSPHATASE TYPES AND TRANSPLACENTAL IGG TRANSPORT

Recently, results have been presented which suggest that placental alk aline phosphatase (FLAP) is an IgG receptor, and that the transplacent al transport of IgG from mother to fetus is dependent on the fetal FLA P genotype. In order to confirm the relationship between the FLAP type s and transplacental IgG transport, we studied fetal (cord serum) IgG levels in relation to FLAP types, quantitative variations in FLAP acti vity, maternal IgG levels and gestation length. Fetal IgG levels and t he fetal/maternal IgG ratio showed no significant correlation with FLA P types and FLAP activity. Thus differences between FLAP types with re spect to transplacental IgG transport are unlikely to play a selective role in the maintenance of the FLAP polymorphism. In accordance with results from previous studies, significant correlations were found wit h maternal IgG levels and gestation length. Perusal of the literature suggests that FLAP is mainly an IgG1 receptor.