title: Immunologic 'ignorance' of vascularized organ transplants in the absence of secondary lymphoid tissue.
abstract: Secondary lymphoid organs (the spleen, lymph nodes and mucosal lymphoid tissues) provide the proper environment for antigen-presenting cells to interact with and activate naive T and B lymphocytes. Although it is generally accepted that secondary lymphoid organs are essential for initiating immune responses to microbial antigens and to skin allografts, the prevailing view has been that the immune response to primarily vascularized organ transplants such as hearts and kidneys does not require the presence of secondary lymphoid tissue. The assumption has been that the immune response to such organs is initiated in the graft itself when recipient lymphocytes encounter foreign histocompatibility antigens presented by the graft's endothelial cells. In contrast to this view, we show here that cardiac allografts are accepted indefinitely in recipient mice that lack secondary lymphoid tissue, indicating that the alloimmune response to a vascularized organ transplant cannot be initiated in the graft itself. Moreover, we demonstrate that the permanent acceptance of these grafts is not due to tolerance but is because of immunologic 'ignorance'.
authors.affiliation: Renal Division, Department of Medicine, Emory University School of Medicine and Veterans Affairs Medical Center, 1670 Clairmont Road, Atlanta, Georgia 30033, USA. fglakkis@emory.edu
authors.forename: F G
authors.initials: FG
authors.lastname: Lakkis
authors.forename: A
authors.initials: A
authors.lastname: Arakelov
authors.forename: B T
authors.initials: BT
authors.lastname: Konieczny
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000818:Animals; D006084:Graft Rejection; D016027:Heart Transplantation / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology; D007519:Isoantigens / Q000276:immunology; D008198:Lymph Nodes / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010581:Peyer's Patches / Q000276:immunology; D016038:Skin Transplantation / Q000276:immunology; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D007519:Isoantigens