Characterization of the expression of MHC proteins in human embryonic stem cells

Human embryonic stem (ES) cells are pluripotent cells that may be used in transplantation medicine. These cells can be induced to differentiate into cells from the three embryonic germ layers both in vivo and in vitro. To determine whether human ES cells might be rejected after transplantation, we examined cell surface expression of the MHC proteins in these cells. Our results show very low expression levels of MHC class I (MHC-I) proteins on the surface of human ES cells that moderately increase on in vitro or in vivo differentiation. A dramatic induction of MHC-I proteins was observed when the cells were treated with IFN-gamma but not with IFN-alpha or -beta. However, all three IFNs induced expression of…