Indirect allorecognition in solid organ transplantation.
Recipient T cell recognition of donor major histocompatibility complex (MHC) alloantigens plays a central role in both acute and chronic rejection of human organ allografts. Two different pathways of T cell recognition of donor MHC alloantigens have been described. The direct pathway involves T cell recognition of intact MHC molecules expressed by donor antigen-presenting cells (APCs). The second, or indirect pathway, operates via T helper cell recognition of peptides derived from the processing and presentation of allogeneic MHC molecules on self-APCs. At the onset of primary acute rejection, recipient CD4+ T cell responses to donor HLA-DR alloantigens are limited to a single dominant determinant present on one of the disparate alloantigens and restricted by one of the responder's HLA-DR molecules. In allograft recipients with recurring episodes of rejection, and/or at the onset of chronic rejection, recipient T cell reactivity may spread to other epitopes within the allogeneic MHC molecule, as well as to other alloantigens expressed by graft tissue. Both quantitative and qualitative alterations in T cell allopeptide reactivity are associated with increased risk of cellular and/or humoral rejection. These studies provide a basis for the design of new therapeutic strategies and for immunologic monitoring of transplant recipients.
Harris
P E
PE
Department of Pathology, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
Cortesini
R
R
Suciu-Foca
N
N
D000818:Animals; D006084:Graft Rejection / Q000276:immunology; D006801:Humans; D007519:Isoantigens; D008285:Major Histocompatibility Complex; D016377:Organ Transplantation; D014181:Transplantation Immunology; D014184:Transplantation, Homologous
D007519:Isoantigens