Clonotype analysis of human alloreactive T cells: a novel approach to studying peripheral tolerance in a transplant recipient.
The recognition of allo-MHC and associated peptides on the surface of graft-derived APC by host T cells (direct pathway allorecognition) plays an important role in acute rejection after organ transplantation. However, the status of the direct pathway T cells in stable long term transplants remains unclear. To detect alloreactive T cell clones in PBL and the allograft during the transplant tolerance, we utilized RT-PCR instead of functional assays, which tend to underestimate their in vivo frequencies. We established alloreactive CD4+ and CD8+ T cell clones from peripheral blood sampled during the stable tolerance phase of a patient whose graft maintained good function for 9 years, 7 without immunosuppression. We analyzed the sequence of TCR Vbeta and Valpha genes and made clonotype-specific probes that allowed us to detect each clone in peripheral blood or biopsy specimens obtained during a 1-year period before and after the rapid onset of chronic rejection. We found an unexpectedly high level of donor HLA-specific T cell clonotype mRNA in peripheral blood during the late tolerance phase. Strong signals for two CD4+ clonotypes were detected in association with focal T cell infiltrates in the biopsy. Chronic rejection was associated with a reduction in direct pathway T cell clonotype mRNA in peripheral blood and the graft. Our data are inconsistent with the hypothesis that direct pathway T cells are involved only in early acute rejection events and suggest the possibility that some such T cells may contribute to the maintenance of peripheral tolerance to an allograft.
Kusaka
S
S
Department of Surgery, University of Wisconsin, Madison, WI 53792, USA.
Grailer
A P
AP
Fechner
J H
JH
Jankowska-Gan
E
E
Oberley
T
T
Sollinger
H W
HW
Burlingham
W J
WJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002461:Cell Line, Transformed; D002908:Chronic Disease; D002999:Clone Cells; D018984:Epitopes, T-Lymphocyte / Q000032:analysis; D005260:Female; D019673:Genes, T-Cell Receptor alpha; D019674:Genes, T-Cell Receptor beta; D006084:Graft Rejection / Q000276:immunology / Q000473:pathology; D006680:HLA Antigens / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D006650:Histocompatibility Testing / Q000379:methods; D006801:Humans; D007108:Immune Tolerance / Q000235:genetics; D016030:Kidney Transplantation / Q000276:immunology* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000473:pathology; D008297:Male; D008969:Molecular Sequence Data; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000473:pathology; D014184:Transplantation, Homologous
D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens