Fetal trophoblast in the placenta forms a barrier between the maternal and fetal blood throughout pregnancy. How this foreign tissue survives its intimate contact with the mother without stimulating or succumbing to a destructive immune response remains one of the riddles of immunology. Current dogma holds that trophoblast may have unique properties that allow it to cope with maternal immunity whilst performing its critical functions at the maternal-fetal interface. The long- term objectives of this application are: to define the expression of MHC and trophoblast-specific antigens on the different placental cell populations, to determine the role of these cells in the regulation of placental growth and function, and to elucidate the mechanism by which the fetal """"""""allograft"""""""" survives in the face of a potentially destructive maternal anti-fetal immune response.
The specific aims encompass five areas of study. 1. The expression of Class I MHC molecules on isolated trophoblast cells will be investigated using monoclonal antibodies to specific H-2 domains (assessed with binding assays, FACS analysis, and immunoprecipitation). Regulation of MHC expression will be investigated in cultured cells and whole placental sections, using both Northern and in situ hybridization with cDNA probes and oligonucleotides. 2. Immunogenicity of trophoblast will be tested by inoculating animals with isolated tropohoblast cells and analyzing the subsequent response with various in vitro and in vivo assays. The effect of such immunization on fertility will be tested. 3. Further analysis of the resistance of trophoblast cells to damage by cellular effectors (LAK cells and activated macrophages) will be conducted, including tests of functional damage in the absence of cells lysis. Trophoblast cells from animals undergoing natural or artificially-induced immune- mediated abortion will be analyzed for aberrant susceptibility. 4. Isolated trophoblast cells will be used to generate monoclonal antibodies toward trophoblast cell surface antigens. Specific cell markers such as these are currently unavailable for mouse trophoblast. 5. The hypothesis that activated maternal cells produce factors capable of regulating placental growth will be tested both in vivo (by perfusing lymphokines into the uterine artery of pregnant females and assessing placental growth) and in vitro (by adding individual lymphokines to cultured trophoblast and assessing cell growth and function).
