Selection of Thymocytes Expressing Transgenic TCR Specific for a Minor Histocompatibility Antigen, H60
- Affiliations
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- 1Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea. eycii@snu.ac.kr
- 2Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul 03760, Korea.
- KMID: 2150851
- DOI: http://doi.org/10.4110/in.2015.15.5.222
Abstract
- Minor histocompatibility antigens are MHC-bound peptides and contribute to the generation of allo-responses after allogeneic transplantation. H60 is a dominant minor H antigen that induces a strong CD8 T-cell response in MHC-matched allogeneic transplantation settings. Here, we report establishment of a TCR transgenic mouse line named J15, wherein T cells express TCRs specific for H60 in complex with H-2K(b), and different fates of the thymocytes expressing J15 TCRs in various thymic antigenic environments. Thymocytes expressing the J15 TCRs were positively selected and differentiated into CD8+ single positive (SP) cells in the thymus of C57BL/6 mice, wherein the cognate antigen H60 is not expressed. However, thymocytes were negatively selected in thymus tissue where H60 was transgenically expressed under the control of the actin promoter, with double-positive stages of cells being deleted. Despite the ability of the H60H peptide (LTFHYRNL) variant to induce cytotoxic activity from H60-specific CTL lines at ~50% of the activity induced by normal H60 peptides (LTFNYRNL), J15-expressing thymocytes were positively selected in the thymus where the variant H60H was transgenically expressed. These results demonstrate that a single amino-acid change in the H60 epitope peptide influences the fate of thymocytes expressing the cognate TCR.
MeSH Terms
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Figure 1 Generation and evaluation of J15 TCR transgenic mice. (A) Diagram depicting cassette vectors pTα and pTβ. Each vector has V-region (Vα and Vβ, respectively) promoter and the complete constant-region (Cα and Cβ, respectively) gene sequences and were subcloned with Vα13D-1 and Jα34-02 for the α chain (using XmaI and NotI), as well as Vβ13-1-02, Dβ2-01, and Jβ2-7-01 for the β chain (using XhoI and SacII). (B) J15 TCR transgenic mice were screened by staining the peripheral blood lymphocytes with anti-V β8.3 mAb, anti-CD8 mAb, and H60-tetramer, followed by flow-cytometric analysis. Vβ8.3 by CD8 and H60-tetramer by CD8 profiles of peripheral-blood lymphocytes from J15 and WT mice. Numbers in plots indicate the frequency of Vβ8.3 expression or H60-tetramer binding of CD8 T cells in the peripheral blood from J15 and WT mice.
Figure 2 Positive selection of J15 TCR transgenic T cells specific for H60. (A) CD4 by CD8 profiles (left) of thymocytes and numbers (right) of each thymic population from J15, OT-I, and WT mice on the B6 background. Numbers at the top of plots indicate total number of thymocytes. (B) Surface expression of Vβ8.3 and Vβ5.2, as well as (C) the binding of the H60- and OVA-tetramer of DN, DP, and CD8 SP thymocytes from J15, OT-I, and WT mice. (D) CD4 by CD8 profiles (left) of splenocytes and numbers (right) of CD4 and CD8 T cells in the spleen from J15, OT-I, and WT mice. (E) Surface expression of Vβ8.3 and Vβ5.2, as well as the binding of the H60- and OVA-tetramer of CD8 T cells in the spleen from J15, OT-I, and WT mice. Numbers in plots indicate the percentage of cells in each quadrant. ***p<0.001; **p<0.01; *p<0.05. Data are representative of three independent experiments and depict the mean±SD.
Figure 3 Negative selection of J15 TCR transgenic T cells specific for H60. (A) CD4 by CD8 profiles (left) of thymocytes and numbers (right) of each thymic population from J15-H60 Tg, J15, OT-I-OVA Tg, and OT-I mice on the B6 background. Numbers at the top of the plots indicate total number of thymocytes. (B) Surface expression of Vβ8.3 and Vβ5.2, as well as (C) the binding of the H60- and OVA-tetramer of DN, DP, and CD8 SP thymocytes from J15-H60 Tg, J15, OT-I-OVA Tg, and OT-I mice. (D) CD4 by CD8 profiles (left) of splenocytes and numbers (right) of CD4 and CD8 T cells in the spleen from J15-H60 Tg, J15, OT-I-OVA Tg, and OT-I mice. (E) Surface expression of Vβ8.3 and Vβ5.2, as well as the binding of the H60- and OVA-tetramer of CD8 T cells in the spleen from J15-H60 Tg, J15, OT-I-OVA Tg, and OT-I mice. Numbers in plots indicate the percentage of cells in each quadrant. ***p<0.001; **p<0.01. Data are representative of three independent experiments and depict the mean±SD.
Figure 4 Lack of negative selection of thymocytes expressing J15 TCR in the presence of H60H. (A) Cytotoxicity assays (left) tested affinities of several different single-amino-acid variants of the H60 epitope by changing the amino acid asparagine (N) residue at P4 of the H60 epitope to different amino acids. The amino acid sequences of the normal H60 and H60H epitope (right), LTFNYRNL and LTFHYRNL, respectively. (B) CD4 by CD8 profiles (left) of thymocytes and numbers (right) of each thymic population from J15-H60H Tg, J15, and H60HTg mice on the B6 background. Numbers at the top of plots indicate the total number of thymocytes. (C) H60-tetramer binding of DN, DP, and CD8 SP thymocytes from J15-H60H Tg, J15, and H60HTg mice. (D) CD4 by CD8 profiles (left) of splenocytes and numbers (right) of CD4 and CD8 T cells in the spleen from J15-H60H Tg, J15, and H60HTg mice. (E) Surface expression of Vβ8.3 and the binding of the H60-tetramer of CD8 T cells in the spleen from J15-H60H Tg, J15, and H60HTg mice. Numbers in plots indicate the percentage of cells in each quadrant. **p< 0.01; *p<0.05; ns, non-significant. Data are representative of two independent experiments and depict the mean±SD.