Cell-mediated xenograft rejection

Abstract

Recent progress in overcoming hyperacute and delayed xenograft rejection makes it important to understand the mechanisms of cell-mediated rejection in xenogeneic transplantation. Recent small animal studies tended to confirm that the strength of this rejection depends on a CD4-mediated indirect response. Although these studies have generally shown the similarity of this xenogeneic response to a human allogeneic response, molecular incompatibilities between humans and pigs that have an effect on the nature of the xeno-reaction are being identified. Efforts to genetically engineer pigs to correct these molecular incompatibilities or to achieve supraphysiologic down-regulation of cell-mediated immunity are at a very early stage of development.