Immunologic Aspects of Organ Transplantation

Susan Smith MN, PhD


June 17, 2002


The immune response to an allogeneic organ transplant is orders of magnitude greater than the nominal immune response because of:

  • alloantigen - individual HLA/MHC peptides that recruit recipient T cells

  • the vast number of T cell clones recruited to the response

  • antigen presentation by donor APCs (direct antigen presentation) and by recipient APCs (indirect antigen presentation).

Until tolerance can be routinely established in all types of solid organ transplant recipients, the success of transplantation will continue to depend largely on the utmost respect for the powerful and complex forces of the human immune system and chronic administration of immunosuppressive therapy. Although the repertoire of agents at our disposal is ever-increasing and ever-improving, clinicians remain faced with the challenge of attaining the often-elusive balance between preventing rejection and imposing drug-related toxicity. These issues will be considered in detail in Chapter 3, "Immunosuppressive Therapies for Organ Transplantation."