A narrow T cell receptor repertoire instructs thymic differentiation of MHC class Ib–restricted CD8+ regulatory T cells
Hye-Jung Kim, … , Jamil R. Azzi, Harvey Cantor
Hye-Jung Kim, … , Jamil R. Azzi, Harvey Cantor
Published November 7, 2023
Citation Information: J Clin Invest. 2024;134(1):e170512. https://doi.org/10.1172/JCI170512.
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Research Article Immunology

A narrow T cell receptor repertoire instructs thymic differentiation of MHC class Ib–restricted CD8+ regulatory T cells

Abstract

Although most CD8+ T cells are equipped to kill infected or transformed cells, a subset may regulate immune responses and preserve self-tolerance. Here, we describe a CD8 lineage that is instructed to differentiate into CD8 T regulatory cells (Tregs) by a surprisingly restricted set of T cell receptors (TCRs) that recognize MHC-E (mouse Qa-1) and several dominant self-peptides. Recognition and elimination of pathogenic target cells that express these Qa-1–self-peptide complexes selectively inhibits pathogenic antibody responses without generalized immune suppression. Immunization with synthetic agonist peptides that mobilize CD8 Tregs in vivo efficiently inhibit antigraft antibody responses and markedly prolong heart and kidney organ graft survival. Definition of TCR-dependent differentiation and target recognition by this lineage of CD8 Tregs may open the way to new therapeutic approaches to inhibit pathogenic antibody responses.

Authors

Hye-Jung Kim, Hidetoshi Nakagawa, John Y. Choi, Xuchun Che, Andrew Divris, Qingshi Liu, Andrew E. Wight, Hengcheng Zhang, Anis Saad, Zhabiz Solhjou, Christa Deban, Jamil R. Azzi, Harvey Cantor

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Figure 1

Identification of Qa-1–FL9–specific TCR.

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Identification of Qa-1–FL9–specific TCR. (A) WT B6 mice were immunized w...
(A) WT B6 mice were immunized with Kb–/–Db–/– DC loaded with FL9 peptide on days 0, 8, and 15. At day 22, Qa-1–FL9–specific CD8 T cells were detected by tets (Qa-1–FL9–PE and Qa-1–FL9–APC) within CD44+CD122+Ly49+ CD8 T cells. (B) TCR repertoire of Qa-1–FL9 Tet+ CD8 T cells. Single Qa-1–FL9–PE+ Qa-1–FL9–APC+ cells were sorted and subjected to sequencing for TCRα and TCRβ. Thirty-nine of TCRα and TCRβ pairs were analyzed based on their TCR V gene segments. Relative usage of TCRα and TCRβ V genes by these Tet+ single cells is depicted by donut charts. (C) TCR repertoire of Qa-1–Hsp60 Tet+ CD8 T cells. Single Qa-1–Hsp60–PE+ Qa-1–Hsp60–APC+ cells were sorted and sequenced for TCRα and TCRβ. Relative usage of TCRα and TCRβ V genes by these Tet+ single cells is depicted by donut chart. (D) Frequency and phenotype of Vα3.2+Vβ5+ cells within Ly49+ CD8 cells in the spleens and LNs of WT B6, Qa-1.D227K–KI and Qa-1–KO mice at 8 weeks of age (n = 6/group). (E) Qa-1–dependent differentiation of FL9 T cells: tet-mediated detection of TCR in 58C hybridoma transduced with FL9.2 and FL9.8 TCR (upper panel). Responsiveness of FL9.2-TCR– and FL9.8-TCR–expressing hybridoma upon stimulation with increasing dose of peptides measured by CD69 expression (lower panel). (F) Measurement of Qa-1–FL9 binding affinity of FL9.2 and FL9.8 TCR. FL9.2 TCR+ and FL9.8 TCR+ hybridoma were labelled with Qa-1–FL9–PE tets and incubated in the presence of anti-Qa-1 antibodies for the indicated time. Percentages of PE+ cells were measured at different time points as a measurement of tet dissociation level. (G) Tg TCR+ cells in TCR+ thymocytes and percent of active-Caspase–3+PD1+ cells in DP (CD4+CD8+) thymocytes in OT-I → WT B6, FL9.2 Tg → WT B6 BM chimera 8 weeks after BM reconstitution. (H) Ki67 and CD44 expression by OT-I and FL9.2 TCR Tg CD8+ T cells was measured as an indication of Ag encounter in the spleen and liver of OT-I → WT B6 and FL9.2 Tg → WT B6 BM chimera 8 weeks after BM reconstitution. OT-1 is also used as a control in Supplemental Figure 6B. *P < 0.05, **P < 0.01, ***P < 0.001, according to Wilcoxon-Mann-Whitney rank sum test.