Expression of the blood-group-related antigens Sialyl Lewis a, Sialyl Lewis x and Lewis y in term placentas of normal, preeclampsia, IUGR- and HELLP-complicated pregnancies.

Lewis antigens belong to the blood group of antigens and mediate cellular adhesion through interaction with selectins. Invasive trophoblasts use an array of adhesion molecules to facilitate cell-cell and cell-extracellular matrix interactions. Here, we examined immunohistochemically the expression of Sialyl Lewis a (sLe(a)), Sialyl Lewis x (sLe(x)) and Lewis y (Le(y)) in term placentas obtained from cases of normal, intrauterine growth retardation (IUGR), preeclamptic (PE) and hemolysis, elevated liver enzymes and low platelets syndrome (HELLP) pregnancies. We report the expression of sLe(x) in third trimester extravillous trophoblasts (EVT). sLe(x) was significantly decreased in IUGR and moderately decreased in PE compared to normal placentas. sLe(x) was additionally found in syncytiotrophoblast, without however any significant differences in staining intensity between normal and pathological cases. sLe(a) was restricted to amnion epithelium. Finally, Le(y) was expressed in cytotrophoblasts and villous endothelial cells. Le(y) expression was significantly upregulated in IUGR and HELLP, whereas there was a trend toward increase in PE compared to normal placentas. The present study suggests that downregulation of sLe(x) in EVT might be associated with IUGR and PE. Furthermore, Le(y), which was recently described as a potent angiogenic factor, is upregulated in placental villi in conditions associated with placental malperfusion.