title: Evidence of T cell clonality in the infectious tolerance pathway: implications toward identification of regulatory T cells.
abstract: We have shown that a rare population of regulatory CD4+ T cells plays a key role in the acquisition of infectious tolerance in rat sensitized recipients of cardiac allografts pretreated with nondepleting anti-CD4 mAb. This study was designed to analyze the TCR Vbeta expression patterns in this transplantation model. First, we used Vbeta-specific RT-PCR to show that there was no differential usage of TCR Vbeta genes by T cells mediating rejection or tolerance. Indeed, graft-infiltrating lymphocytes expressed most of the 22 known rat TCR Vbeta genes in both recipient groups, suggesting unrestricted TCR Vbeta repertoire in alloreactive T cells. Then, we applied CDR3 spectrotyping of TCR beta-chain to assess the clonality of T cells at different anatomic sites. CDR3 size restriction, indicative of the presence of T cell clones, was observed in graft-infiltrating lymphocytes but not in draining lymph nodes or spleen of tolerant hosts. Consisent with the clonal expansion, T cells in tolerated grafts exhibited the memory phenotype at a much higher percentage as compared with peripheral lymphoid organs. Moreover, in tolerated graft-infiltrating lymphocytes, the CD3 size restriction occurred in limited Vbeta gene families, with Vbeta8.1 and Vbeta18 most frequently detected. Hence, T cells at the graft site of tolerant recipients contain T cell clones expressing selective Vbeta genes. This phenotypic characteristics of the tolerogenic GILs may potentially be used as a novel marker to identify operational regulatory T cells in organ allograft recipients.
authors.affiliation: The Dumont-UCLA Transplant Center, Rm. 77-120 CHS, 10833 Le Conte Ave, Los Angeles, CA 90095, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhai
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Hammer
authors.forename: R W
authors.initials: RW
authors.lastname: Busuttil
authors.forename: H D
authors.initials: HD
authors.lastname: Volk
authors.forename: J W
authors.initials: JW
authors.lastname: Kupiec-Weglinski
mesh_terms: D000818:Animals; D002999:Clone Cells; D022801:Complementarity Determining Regions; D006084:Graft Rejection / Q000276:immunology / Q000378:metabolism; D016027:Heart Transplantation / Q000276:immunology*; D007108:Immune Tolerance; D007136:Immunoglobulins; D007156:Immunologic Memory; D007239:Infections / Q000276:immunology*; D008214:Lymphocytes / Q000473:pathology / Q000502:physiology; D008297:Male; D009206:Myocardium / Q000276:immunology / Q000473:pathology; D043025:Oligoclonal Bands; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D011920:Rats, Inbred WF; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D022801:Complementarity Determining Regions; D007136:Immunoglobulins; D043025:Oligoclonal Bands; D016693:Receptors, Antigen, T-Cell, alpha-beta