title: CD4+ T cell recognition of a single discordant HLA-A2-transgenic molecule through the indirect antigen presentation pathway induces acute rejection of murine cardiac allografts.
abstract: To further define the role of indirect allorecognition, cardiac allografts from HLA-A2-transgenic (HLA-A2+) C57BL/6 mice were heterotopically transplanted into normal C57BL/6, CD4 T cell-knockout (KO) C57BL/6 mice, CD8 T cell-KO C57BL/6 mice, fully MHC-discordant BALB/c mice (allogeneic control), and HLA-A2+ C57BL/6 mice (syngeneic control). HLA-A2+ grafts were acutely rejected when transplanted into BALB/c mice (mean survival time: 10+/-0.8 days), normal C57BL/6 mice (mean survival time: 16.5+/-2.1 days) as well as CD8-KO mice (mean survival time: 12.8+/-1.3 days). Histopathological analysis revealed classical acute cellular rejection with moderate to severe diffuse interstitial CD4+ and CD8+ cellular infiltrates and significant intra-graft deposition of IgG and complement. In contrast, HLA-A2+ grafts were not rejected when transplanted into CD4-KO mice or HLA-A2+ mice. CD8-KO recipients treated with an anti-CD4 monoclonal antibody, but not with an anti-NK monoclonal antibody, failed to reject their allografts with prolonged administration of antibody (30 days). Spleen cells from mice rejecting HLA-A2+ allografts failed to lyse HLA-A2+ target cells indicating a lack of involvement of CD8+ T cells in the rejection process. In contrast, spleen cells from rejecting animals proliferated significantly to both HLA-A2+ cells and to a peptide derived from the HLA-A2 molecule. Development of anti-HLA-A2 antibodies was observed in all animals rejecting HLA-A2+ allografts. These results suggest that indirect allorecognition of donor MHC class I molecules leads to rejection of cardiac allografts and development of alloantibodies in this unique transplant model in which there is a single MHC discordance between donor and recipient.
authors: Transplantation Section, Department of Surgery, Washington University School of Medicine, Box 8109-3328.CSRB, 660 South Euclid Avenue, St. Louis, MO 63110-1093, USA.
authors: C R
authors: CR
authors: Smith
authors: A
authors: A
authors: Jaramillo
authors: W
authors: W
authors: Liu
authors: Y
authors: Y
authors: Tu
authors: Z
authors: Z
authors: Kaleem
authors: C J
authors: CJ
authors: Swanson
authors: T
authors: T
authors: Mohanakumar
mesh_terms: D000208:Acute Disease; D000818:Animals; D000906:Antibodies / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D002455:Cell Division; D000939:Epitopes; D006084:Graft Rejection / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics; D014184:Transplantation, Homologous / Q000276:immunology
chemical_list: D000906:Antibodies; D000939:Epitopes; D015789:HLA-A2 Antigen