Localization of α2-Macroglobulin Receptor/Low-Density Lipoprotein Receptor in Third-Trimester Human Placentas: A Preliminary Immunohistochemical Study

Abstract

The α2-macroglobulin receptor/low-densitiy lipoprotein receptor-related protein (α2-M-R/LRP) is involved in a variety of transcellular transportations, e.g. of apolipoprotein E, and represents an inhibitor of proteinases. After creation of monoclonal antibodies of the α- and β-subunits of the α2-M-R/LRP and its receptor-associated protein, we have tested their distribution in five 3rd-trimester placentas, using cryosections, immunohistochemically and by immunofluorescence. All three monoclonal antibodies showed positive staining in villous and extravillous cytotrophoblasts and intravillous vessels, but not in syncytiotrophoblasts. Thus, α2-M-R/LRP plays a possible role in the transplacental nutritional transportation process. It is necessary to search the distribution of α2-M-R/LRP under pathological conditions, like fetal growth retardation and preeclampsia.