PROBLEM: The nature of major histocompatibility complex (MHC) antigen expression on rat placentas, trophoblast cell lines, and tumors derived from trophoblast cells was explored.
METHOD OF STUDY: Cytohistochemical and flow cytometric analysis and molecular techniques.
RESULTS: MHC antigen expression and genomic imprinting on the placenta and on trophoblast cells varies with the time of gestation and with the type of MHC antigen.
CONCLUSIONS: There is no correlation in trophoblast cells between class I expression and cell ploidy, on the one hand, and malignant potential, on the other hand. Genomic imprinting of class I antigens in the rat placenta is a quantitative phenomenon.