Differences in the cell surface antigens of prolactin-producing cells of human decidual and pituitary tissues

Anterior pituitary cells and other endocrine cells which synthesize and release protein hormones share the cell surface ganglioside antigens A2B5 and 3G5. In addition, these peptide hormone-producing cells contain chromogranin, a major protein component of secretory vesicles. Since human decidual cells synthesize and release a PRL that has chemical and biological properties indistinguishable from those of pituitary PRL, we examined by immunochemical techniques whether decidual cells also contain cell surface antigens A2B5, 3G5, and chromogranin. In these studies, human decidual tissue from three pregnancies and human and rat pituitary tissues were processed and stained with mouse monoclonal antibodies to A2B5, 3G5, and chromogranin by indirect immunofluorescence using fluorescein-conjugated sheep antimouse gamma-globulin. In all instances, the pituitary and pancreatic tissue stained strongly with the monoclonal antibodies to the cell surface antigens, but the decidual tissues from the three pregnancies did not. The pituitary and pancreatic cells also stained strongly with the monoclonal antibody (LK 2H10) to chromogranin, but the decidual tissues had no reactivity. In control experiments, the decidual tissues stained strongly with a monoclonal antibody to HLA antigens, and none of the tissues stained with nonimmune gamma-globulin. These results strongly suggest that the PRL-producing cells of human decidua and pituitary have different cell surface antigens. The observation that decidual cells do not contain chromogranin is consistent with previous biochemical studies suggesting that decidual PRL is not stored in secretory granules. The differences in the subcellular localization of PRL in decidual and pituitary tissues may explain, in part, the differences in the regulation of PRL release from these tissues.