Cellular Characterization of the 91kDa-ectopic Ascitic Antigen Sharing Antigenicity with MRP8 in the Human Placenta as Revealed by Immunoelectron Microscopical Colloidal-gold Techniques

Abstract

Summary: Cellular characterization of the 91kDa-ectopic ascitic protein that exhibits pregnancy-associated and tumourrelated dynamics has been examined in the human placenta using an electron microscopic immunocolloidal-gold technique. This protein was initially isolated from the ascitic fluids of a patient suffered from ovarian and uterine cancers with mixed mesodermal tumours, and determined to be sharing antigenicity with the 28kDa-oncodevelopmental protein and a calcium-binding protein; MRP8/CFA, respectively. Placentas obtained were divided into three groups by their gestational periods. Small chorionic villous tissues were embedded in Lowicryl K4M resin or Epon 812 resin. Specific and higher labellings by gold-particles were obtained in sections of Lowicryl resin and, then, recognized in mesenchyme-derived cells and/or myeloid lineages; such as placental tissue macrophages (Hofbauer cells), fibroblasts, foetal myelomonocytic cells including endothelial cells, etc., in the first and second trimesters. So far, the pattern of antigenic appearances changed depending on the stage of gestation. On the other hand, 91kDa-protein was also determined in the syncytiotrohpoblast, but not in cytotrophoblasts at whenever been examined. It is assumed that the antigenic expression in syncytiotrophoblasts might be reflected to be absorbed or incorporated from those of foetal or maternal origins, and the antibody used in this study should be sensitive to the antigenic epitope derived from those of myeloid lineages. In the light of these results, hypotheses concerning mechanisms of both transplacental permeability of substances by the placental barrier and cell/tissue differentiation by calcium-binding (and/or -depending) proteins such as 91kDa-protein, MRP8, etc.; presumable the S-100 protein family, are discussed further.

Tissue Expression of the S100 Protein Family-related MRP8 Gene in Human Chorionic Villi by in situ Hybridization Techniques

“…We have previously isolated three pregnancyassociated and tumour-related proteins from human placenta and ascites of ovarian and uterine cancer patients6"6 '17). Two of these proteins, a 91 kDa-oncofetoplacental protein (91-0FP) and 28 kDa-oncodevelopmental protein (28-ODP), were coincidentally and synchronously expressed by syncytiotrophoblasts, placental-tissue macrophagelike cells (Hofbauer cells), fibroblast-like cells, endothelial cells and foetal monocytes of the chorionic villi during the first two trimesters, and also in ovarian adenocarcinoma cells, uterine nonkeratinizing cells and glossy cells, and vaginal squamous carcinoma cells9, 11,15,22,23,25). The 28-ODP may be a member of the oncofetoplacental protein-superfamily6).…”