The self-peptide repertoire plays a critical role in transplant tolerance induction
Eric T. Son, … , Nicole A. Mifsud, Alexandra F. Sharland
Eric T. Son, … , Nicole A. Mifsud, Alexandra F. Sharland
Published August 24, 2021
Citation Information: J Clin Invest. 2021;131(21):e146771. https://doi.org/10.1172/JCI146771.
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Research Article Immunology

The self-peptide repertoire plays a critical role in transplant tolerance induction

Abstract

While direct allorecognition underpins both solid organ allograft rejection and tolerance induction, the specific molecular targets of most directly alloreactive CD8+ T cells have not been defined. In this study, we used a combination of genetically engineered major histocompatibility complex class I (MHC I) constructs, mice with a hepatocyte-specific mutation in the class I antigen-presentation pathway, and immunopeptidomic analysis to provide definitive evidence for the contribution of the peptide cargo of allogeneic MHC I molecules to transplant tolerance induction. We established a systematic approach for the discovery of directly recognized pMHC epitopes and identified 17 strongly immunogenic H-2Kb–associated peptides recognized by CD8+ T cells from B10.BR (H-2k) mice, 13 of which were also recognized by BALB/c (H-2d) mice. As few as 5 different tetramers used together were able to identify a high proportion of alloreactive T cells within a polyclonal population, suggesting that there are immunodominant allogeneic MHC-peptide complexes that can account for a large component of the alloresponse.

Authors

Eric T. Son, Pouya Faridi, Moumita Paul-Heng, Mario L. Leong, Kieran English, Sri H. Ramarathinam, Asolina Braun, Nadine L. Dudek, Ian E. Alexander, Leszek Lisowski, Patrick Bertolino, David G. Bowen, Anthony W. Purcell, Nicole A. Mifsud, Alexandra F. Sharland

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Figure 12

Tetramer-positive alloreactive cells are phenotypically distinct from bulk CD8+ T cells.

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Tetramer-positive alloreactive cells are phenotypically distinct from bu...
Surface markers of naive, effector, and memory status were assessed in bulk and tet+ CD8+ T cells from naive or transplanted mice. Relatively subtle phenotypic changes in the CD8+ T cell population were far more obvious when tet+ cells were examined. (A) In naive mice, tet+ liver leukocytes contained all CD8+ T cell subsets, whereas in mice having rejected a primary or secondary graft, tet+ cells were exclusively antigen-experienced, comprising both central memory and effector/resident memory cells. (B) Following exposure to H-2Kb in the liver, CD62L+ tet+ cells were no longer observed, and the majority of cells expressed markers of liver-homing or residency (CD69 and/or CXCR6). (C) By 7 days after inoculation with AAV-Kb, tet+ cells in the liver have upregulated PD-1, TIGIT, Tim-3, and LAG-3. While strong PD-1 expression persists through d84 after tolerance induction, expression of LAG-3, Tim-3, and to a lesser extent TIGIT in the tet+ population declines over this time. (D) All tet+ cells isolated from rejecting or tolerated grafts on protocol d14 were antigen-experienced. Tethi cells, only present in rejecting grafts, were uniformly CD62L-negative and PD-1hi. (A, C, and D) Representative flow plots (from n = 3). (B) Data are shown as mean ± SEM (n = 3).