Endogenous heparin-binding lectin activity in human placenta: purification and developmental expression.

Human placental extracts contain a herapin-inhibitable lectin activity. The lectin, which closely resembles those from chicken and rat tissues, was purified by heparin-affinity chromatography. It shares many properties with the previously reported lectins, including hapten specificity, molecular weight of monomers, and immunological cross-reactivity. Sections from different stages of placental development, stained by immunohistochemistry procedures using lectin-specific antibody, showed that the lectin was initially present only in cytotrophoblasts of early first trimester villi. Later in the first trimester, both cytotrophoblasts and syncytiotrophoblasts were stained positively for lectin. From second trimester to term, the lectin was seen only in syncytiotrophoblasts.