Globoside expression within the human placenta

This report demonstrates the presence of the neutral glycosphingolipid, glo boside, on the villous trophoblast layer of human placenta. Immunoreactivit y for globoside which is the receptor used by human parvovirus B19 was stro ngest in villous trophoblast cells of first trimester placentae, with dimin ished reactivity in second trimester placentae, and a near lack of staining for the antigen in those of third trimester. This relative reduction in gl oboside-specific immunoreactivity in placentae of increasing gestational ag es was confirmed using thin-layer chromatographic analyses of extracted neu tral glycolipids from the syncytiotrophoblast layer and cytotrophoblast cel ls of first and third trimester placental villi. The presence of globoside on the protective trophoblast layer of the villi provides a potential pathw ay whereby B19 may be transmitted from an infected mother to the fetus. The virus once across the placental barrier, may gain access to its erythroid precursor target cells within fetal villus capillaries. The observed change found in globoside immunoreactivity correlates well with the observation t hat fetal outcome is worse when maternal infection occurs during first or s econd trimester as compared to an infection occurring near term. The reason for this observed difference in fetal outcome may be due not only to the p resence of more target cells potentially to infect during the first and sec ond trimesters, but also to the greater number of viral receptors present o n the villous trophoblast layer. (C) 1999 W. B. Saunders Company Ltd.