Characterization of the human antiporcine immune response - A prerequisiteto xenotransplantation

Successful xenotransplantation necessitates solving problems of hyperacute rejection and understanding the cellular immune responses that occur. Consi derable progress has been made in our understanding of the molecular geneti c basis of the rapid hyperacute antibody-mediated rejection mechanisms that occur in xenogeneic organ rejection. In parallel, strategies involving the use of transgenic animals expressing complement inhibitors are beginning t o offer encouraging evidence that hyperacute rejection can be overcome. A g reater understanding of cell-mediated immune interactions is now required t o achieve long-term xenograft survival. Current studies are focused on T ce ll receptor (TCR)/major histocompatibility complex (MHC) and costimulatory signals that activate human CD4 and CD8 T cells.