Transplantation Immunology: Mechanisms of Rejection, Tolerance Induction, and Clinical Translation

This chapter reviews the immunological basis of allograft rejection, covering recent advances in allorecognition pathways, T cell- and antibody-mediated rejection mechanisms, and the role of non-classical immune cells in graft surveillance. It evaluates current immunosuppressive regimens and explores the molecular and cellular basis of operational tolerance, including emerging strategies — such as regulatory T cell therapy, co-stimulation blockade, and mixed chimerism protocols — aimed at achieving tolerance without long-term immunosuppression. The chapter also addresses immunological challenges unique to transplantation of specific organs and the evolving immunological considerations in xenotransplantation research.