Bovine Trophoblast Non-classical MHC Class I Proteins

Extremely polymorphic and ubiquitously expressed classical MHC-I (MHC-Ia) proteins, which present the foreign antigenic peptides to CD8+ T lymphocytes, are involved in acceptance or rejection of tissue grafts based on the degree of similarity of these proteins among the cells of donor and recipient. Discovery of non-classical MHC-I proteins such as Human Leukocyte Antigen-G (HLA-G) in humans and Qa-2 in mice, led to a new paradigm of immune tolerance to fetus. Class-Ib proteins are important glycoproteins which are important modulators of maternal immune system during pregnancy. During third trimester, bovine fetal trophoblast cells express both MHC-Ia and MHC-Ib proteins, which suggests that these proteins play a role in separation of the fetal placenta during parturition. The MHC-Ib proteins expressed during third trimester are bovine leukocyte antigen (BoLA) NC1*00401, NC1*00501, NC2*00102, NC3*00101 and NC4*00201 proteins.N*01701, N*01802, NC1*00501, NC3*00101 and NC4*00201 proteins showed the cell-surface expression as identified with transfection assays performed in murine P815 and human K562 cells.