Processed MHC class I alloantigen as the stimulus for CD4+ T-cell dependent antibody-mediated graft rejection

The traditional view of graft rejection is one of direct recognition of allogeneic MHC molecules by effector T cells, the phenotype of which may be predicted by the nature of the MHC disparity. In this article, Andrew Bradley and colleagues discuss recent evidence that suggests this view may be an oversimplification, and argue that additional effector mechanisms, such as alloantibody, need to be reconsidered.