Characterization of human αβTCR repertoire and discovery of D-D fusion in TCRβ chains

The characterization of the human T-cell receptor （TCR） repertoire has made remarkable progress, with most of the work focusing on the TCRβ chains. Here, we ana- lyzed the diversity and complexity of both the TCRa and TCRβ repertoires of three healthy donors. We found that the diversity of the TCRα repertoire is higher than that of the TCRβ repertoire, whereas the usages of the V and J genes tended to be preferential with similar TRAV and TRAJ patterns in all three donors. The V-J pairings, like the V and J gene usages, were slightly preferential. We also found that the TRDV1 gene rearranges with the majority of TRAJ genes, suggesting that TRDV1 is a shared TRAV/DV gene （TRAV42/DV1）. Moreover, we uncovered the presence of tandem TRBD （TRB D gene） usage in -2% of the productive human TCRβ CDR3 sequences.

Profiling the pattern of the human T-cell receptorγδcomplementary determinant region 3 repertoire in patients with lung carcinoma via high-throughput sequencing analysis

γδT cells function as sentinels in early host responses to infections and malignancies.Specifically,γδT cells recognize tumor-associated stress antigens via T-cell receptor(TCR)γδand play important roles in the antitumor immune response.In this study,we characterized the pattern of the human TCRγδcomplementary determinant region 3(CDR3)repertoire in patients with lung carcinoma(LC)via high-throughput sequencing.The results showed that the diversity of CDR3δwas significantly reduced,and that of CDR3γwas unchanged in LC patients compared with healthy individuals;in addition,LC patients shared significantly more CDR3δsequences with each other than healthy individuals.The CDR3 length distribution and N-addition length distribution did not significantly differ between LC patients and healthy individuals.In addition,the CDR3 repertoire tended to use more Vδ2 and fewer Vδ1 germline gene fragments among LC patients.Moreover,we found a combination of four TCRγδrepertoire features that focus on CDR3δand can be used as a biomarker for LC diagnosis.Our research suggests that the TCRγδCDR3 repertoire changed in LC patients due to the antitumor immune response byγδT cells in vivo,and these changes primarily focus on the amplification of certain tumor-specific CDR3δclones among patients.This study demonstrates the role ofγδT cells from the TCRγδCDR3 repertoire in tumor immunity and lays the foundation for elucidating the mechanism underlying the function ofγδT cells in antitumor immunity.

Changes in the T-cell receptor Vβ gene repertoire after allogeneic hematopoietic stem cell transplantation

Background We distinguished graft-versus-host disease (GVHD) from graft-versus-leukemia (GVL) effects and to investigate the distribution of T-cell receptor (TCR) Vβ gene repertoire in individuals with leukemia before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT).Methods Peripheral blood mononuclear cells (PBMC) were obtained from 10 normal individuals, 8 donors and 11 patients with leukemia before and after transplantation. Polymerase chain reaction (PCR) amplification of complementarity-determining region 3 (CDR3) of 24 TCR Vβ genes was used to examine serial samples of PBMC. The PCR products were further analyzed by genescan to evaluate clonality of T cells.Results The 24 TCR Vβ gene repertoire displayed highly diverse and polyclonal spectratypes in all normal individuals and 4 of 8 donors. Anoth er 4 donors expressed part of the 24 TCR Vβ subfamily and 1 donor had oligoclonality. The expressions of the 24 TCR Vβ subfamilies were skewed and restric ted in 11 leukemia patients before and after transplantation. Some absences of 24 TCR Vβ subfamily expression were quite similar between the recipients pro-transplantation and related donors. The number of subfamilies expressed increased over time post-transplantation, but the restricted expressions of the subfamily could last 6-30 months after transplantation. All patients with GVHD and some without GVHD exhibited T cell clonal expansion. The expansive T cell clone was distributed in Vβ 2-3, 16-17, 18-19, 21 and Vβ 23 in patients with GVHD and in Vβ 7, 9, 16 and 19 in patients without GVHD. One patient with syngeneic-HSCT (syn-HSCT) had Vβ 15 and 16 T cell expansion after transplantation. One patient displayed Vβ 18 T cell expansion after donor lymphocyte infusion (DLI).Conclusions Normal individuals express the entire 24 TCR Vβ ge ne repertoire and have polyclonal distribution. However, the TCR Vβ gene repertoire is only partially expressed in some donors. The TCR Vβ gene repertoire is restrictedly expressed in a skew fashion in patients with leukemia before and after transplantation. The number of TCR Vβ gene subfamilies increases over time post- transplantation. GVHD and GVL effects may induce the proliferation of T cell clones.Clinical GVL response may be distinguished from GVHD alloreactivity through the host MHC antigen.

αβ T cell receptors as predictors of health and disease

The diversity of antigen receptors and the specificity it underlies are the hallmarks of the cellular arm of the adaptive immune system. T and B lymphocytes are indeed truly unique in their ability to generate receptors capable of recognizing virtually any pathogen. It has been known for several decades that T lymphocytes recognize short peptides derived from degraded proteins presented by major histocompatibility complex （MHC） molecules at the cell surface. Interaction between peptide-MHC （pMHC） and the T cell receptor （TCR） is central to both thymic selection and peripheral antigen recognition. It is widely assumed that TCR diversity is required, or at least highly desirable, to provide sufficient immune coverage. However, a number of immune responses are associated with the selection of predictable, narrow, or skewed repertoires and public TCR chains. Here, we summarize the current knowledge on the formation of the TCR repertoire and its maintenance in health and disease. We also outline the various molecular mechanisms that govern the composition of the pre-selection, naive and antigen-specific TCR repertoires. Finally, we suggest that with the development of high-throughput sequencing, common TCR ＇signatures＇ raised against specific antigens could provide important diagnostic biomarkers and surrogate predictors of disease onset, progression and outcome.

The Roles of Orphan Nuclear Receptors in the Development and Function of the Immune System

Hormones and their receptors regulate cell growth,differentiation and apoptosis and also play important roles in immune function.Recent studies on the subfamily of the orphan nuclear receptors known as retinoid-acid related orphan receptors (ROR) have shed important insights on the roles of this group of nuclear proteins in the development and function of the immune system.RORα regulates inflammatory cytokine production in both innate and adaptive immune system while RORγ regulates the normal development of T lymphocyte repertoire and secondary lymphoid organs.Cellular & Molecular Immunology.2004;1(6):401-407.

Bone marrow stromal cell line co-transfected with IL-2 and IL-3 genes can accelerate restoration of T-cell immunity in allo-BMT mice

Background After T-cell depleted allogeneic bone marrow transplantation, impaired immune reconstitution is a major cause of morbidity and mortality in the recipient The purpose of this study was to observe the effects of the gene-engineered bone marrow stromal cell line QXMSC1-IL-2+IL-3 on the reconstitution of T-cell immunity in allo-BMT mice Methods The bone marrow stromal cell line QXMSC1 was co-transfected with IL-2 and IL-3 genes using a Tet-on gene expression system T lymphocyte subset counts per spleen were analyzed by flow cytometry Lymphocyte proliferation response to ConA was examined to evaluate T-cell function CDR3 spectratyping techniques were performed to evaluate TCR repertoire diversity at various time points post-transplantation Results Gene engineered bone marrow stromal cell line QXMSC1-IL-2+IL-3 could express IL-2 and IL-3 (1300 ng·day -1 ·10 -6 cells and 1100 ng·day -1 ·10 -6 cells, respectively) under the control of doxycycline QXMSC1-IL-2+IL-3 in combination with allogeneic bone marrow could significantly increase the counts of CD4 + and CD8 + T cell, 1.72 and 1.27-fold respectively at week 3 compared with TCD-BMT group ( P <0.01); make CD4 +/CD8 + ratio return to normal level at week 4; enhance splenocytes mitotic response to ConA ( P <0.01), and accelerate restoration of TCR repertoire diversity in the lethally irradiated mice ( P <0.05) KH*2/5DConclusion The gene transduced stromal cell line QXMSC1-IL-2+IL-3 is able to accelerate T-cell immunity in allo-BMT mice