Presence of Vicia graminea lectin- and Vicia unijuga lectin-binding (Vgu) glycoproteins in human fetal membranes and some of their biochemical properties

Abstract

We have previously reported that Vicia graminea lectin (VGA)- and Vicia unijuga lectin (VUA)-binding glycoproteins (Vgu glycoproteins), malignant tumor-associated antigens, exist in human meconium and amniotic fluid. To examine the origin of Vgu glycoprotein, their presence, some of their chemical and serological properties and their biosynthesis in the human fetal membrane, amnion and chorion laeve and accompanying membrane cells were examined. Perchloric acid-soluble fractions were prepared from human amnion and chorion laeve, after which VUA-binding components (Vgu glycoproteins) were separated by HPLC and affinity chromatography using immobilized VUA. Biosynthesis of the antigens in primary cultured cells prepared from the amnion and chorion laeve were examined by pulse-labeling and immunoprecipitation using immobilized VUA and compared with those in cultured human cancer cells. The results indicated that the serological properties of VUA-binding components in fetal membranes were similar to those of meconium and amniotic fluid, that many molecular species of VUA-binding components were synthesized in amnion and chorion laeve cells and that about 40–50% of antigens synthesized are secreted from cells while antigens synthesized in cultured cancer cells human were hardly secreted with more than 95% of the antigens remaining in the cells. From these results, we concluded that a large part of Vgu glycoproteins found in amniotic fluid is synthesized in cells of the amnion and chorion laeve and secreted into the fluid, and that Vgu glycoproteins synthesized in cancer cells were not secreted, rather they were retained in the cells.