Immunohistochemical localization of a beta-D-galactoside-binding lectin at the human maternofetal interface

The 14 kD S-type lectin from human placenta may have a role in regulating the maternal immune response to fetal antigens. In this study, an immunoperoxidase technique was used to determine the distribution of the lectin at the human maternofetal interface. Tissue obtained during the first trimester of pregnancy and at term was used. The lectin was not detectable in either the villous syncytiotrophoblast or the underlying cytotrophoblast in first-trimester tissue, although some cells of the cytotrophoblast columns were reactive. It was also not detectable in villous or extravillous trophoblast populations at term. In contrast, strong reactivity was found in decidual stromal cells throughout gestation, and endometrial stromal cells were also positive. The lectin is, therefore, not a component of the immunosuppressive factors associated with syncytiotrophoblast membranes, but may have a role in either the decidual control of trophoblast migration or some functions unrelated to pregnancy, or both.