Downregulation of cytolytic activity of human effector cells by transgenic expression of human PD-ligand-1 on porcine target cells.

Cellular rejection is a relevant hurdle for successful pig-to-primate xenotransplantation. We have shown previously that the induction of a human anti-pig T cell response (in vitro activation of CD4(+) T cells) can be suppressed by the overexpression of human negative costimulatory ligands (e.g.