Canine peripheral non-conventional TCRαß+ CD4-CD8α- double-negative T cells show T helper 2-like and regulatory properties.

The dog is an important companion animal and also serves as model species for human diseases. Given the central role of T cells in immune responses, a basic understanding of canine conventional T cell receptor (TCR)αß+ T cells, comprising CD4+ single-positive (sp) T helper (Th) and CD8α+ sp cytotoxic T cell subsets, is available. However, characterization of canine non-conventional TCRαß+ CD4+CD8α+ double-positive (dp) and TCRαß+ CD4-CD8α- double-negative (dn) T cells is limited. In this study, we performed a comprehensive analysis of canine dp and dn T cells in comparison with their conventional counterparts. TCRαß+ T cells from peripheral blood of healthy dogs were sorted according to their CD4/CD8α phenotype into four populations (i.e. CD4+ sp, CD8α+ sp, dp, and dn) and selected surface markers, transcription factors and effector molecules were analyzed ex vivo and after in vitro stimulation by RT-qPCR. Novel characteristics of canine dp T cells were identified, expanding the previously characterized Th1-like phenotype to Th17-like and Th2-like properties. Overall, mRNA expression of various Th cell-associated cytokines (i.e. IFNG, IL17A, IL4, IL13) in dp T cells upon stimulation highlights their versatile immunological potential. Furthermore, we demonstrated that the CD4-CD8α- dn phenotype is stable during in vitro stimulation. Strikingly, dn T cells were found to express highest mRNA levels of type 2 effector cytokines (IL4, IL5, and IL13) upon stimulation. Their strong ability to produce IL-4 was confirmed at the protein level. Upon stimulation, the percentage of IL-4-producing cells was even higher in the non-conventional dn than in the conventional CD4+ sp population. Constitutive transcription of IL1RL1 (encoding IL-33Rα) further supports Th2-like properties within the dn T cell population. These data point to a role of dn T cells in type 2 immunity. In addition, the high potential of dn T cells to transcribe the gene encoding the co-inhibitory receptor CTLA-4 and to produce the inhibitory cytokine IL-10 indicates putative immunosuppressive capacity of this population. In summary, this study reveals important novel aspects of canine non-conventional T cells providing the basis for further studies on their effector and/or regulatory functions to elucidate their role in health and disease.

Exploitation of CD3ζ to enhance TCR expression levels and antigen-specific T cell function.

The expression levels of TCRs on the surface of human T cells define the avidity of TCR-HLA/peptide interactions. In this study, we have explored which components of the TCR-CD3 complex are involved in determining the surface expression levels of TCRs in primary human T cells. The results show that there is a surplus of endogenous TCR α/ß chains that can be mobilised by providing T cells with additional CD3γ,δ,ε,ζ chains, which leads to a 5-fold increase in TCR α/ß surface expression. The analysis of individual CD3 chains revealed that provision of additional ζ chain alone was sufficient to achieve a 3-fold increase in endogenous TCR expression. Similarly, CD3ζ also limits the expression levels of exogenous TCRs transduced into primary human T cells. Interestingly, transduction with TCR plus CD3ζ not only increased surface expression of the introduced TCR, but it also reduced mispairing with endogenous TCR chains, resulting in improved antigen-specific function. TCR reconstitution experiments in HEK293T cells that do not express endogenous TCR or CD3 showed that TCRα/ß and all four CD3 chains were required for optimal surface expression, while in the absence of CD3ζ the TCR expression was reduced by 50%. Together, the data show that CD3ζ is a key regulator of TCR expression levels in human T cells, and that gene transfer of exogenous TCR plus CD3ζ improved TCR surface expression, reduced TCR mispairing and increased antigen-specific function.

Deciphering Abdominal Aortic Diseases Through T-Cell Clonal Repertoire of Perivascular Adipose Tissue.

BACKGROUND: Recent studies suggest that immune-mediated inflammation of perivascular adipose tissue of abdominal aortic aneurysms (AAAs) contributes to disease development and progression. Whether the perivascular adipose tissue of AAA is characterized by a specific adaptive immune signature remains unknown. METHODS AND RESULTS: To investigate this hypothesis, we sequenced the T-cell receptor ß-chain in the perivascular adipose tissue of patients with AAA and compared it with patients with aortic occlusive disease, who share the former anatomical site of the lesion and risk factors but differ in pathogenic mechanisms. Our results demonstrate that patients with AAA have a lower repertoire diversity than those with aortic occlusive disease and significant differences in variable/joining gene segment usage. Furthermore, we identified a set of 7 public T-cell receptor ß-chain clonotypes that distinguished AAA and aortic occlusive disease with very high accuracy. We also found that the T-cell receptor ß-chain repertoire differentially characterizes small and large AAAs (aortic diameter<55 mm and ≥55 mm, respectively). CONCLUSIONS: This work supports the hypothesis that T cell-mediated immunity is fundamental in AAA pathogenesis and opens up new clinical perspectives.

Germline-like TCR-α chains shared between autoreactive T cells in blood and pancreas.

Human type 1 diabetes (T1D) is caused by autoimmune attack on the insulin-producing pancreatic beta cells by islet antigen-reactive T cells. How human islet antigen-reactive (IAR) CD4+ memory T cells from peripheral blood affect T1D progression in the pancreas is poorly understood. Here, we aim to determine if IAR T cells in blood could be detected in pancreas. We identify paired αß (TRA/TRB) T cell receptors (TCRs) in IAR T cells from the blood of healthy, at-risk, new-onset, and established T1D donors, and measured sequence overlap with TCRs in pancreata from healthy, at risk and T1D organ donors. We report extensive TRA junction sharing between IAR T cells and pancreas-infiltrating T cells (PIT), with perfect-match or single-mismatch TRA junction amino acid sequences comprising ~29% total unique IAR TRA junctions (942/3,264). PIT-matched TRA junctions were largely public and enriched for TRAV41 usage, showing significant nucleotide sequence convergence, increased use of germline-encoded versus non-templated residues in epitope engagement, and a potential for cross-reactivity. Our findings thus link T cells with distinctive germline-like TRA chains in the peripheral blood with T cells in the pancreas.

MAIT cell-MR1 reactivity is highly conserved across multiple divergent species.

Mucosal-associated invariant T (MAIT) cells are a subset of unconventional T cells that recognize small molecule metabolites presented by major histocompatibility complex class I related protein 1 (MR1), via an αß T cell receptor (TCR). MAIT TCRs feature an essentially invariant TCR α-chain, which is highly conserved between mammals. Similarly, MR1 is the most highly conserved major histocompatibility complex-I-like molecule. This extreme conservation, including the mode of interaction between the MAIT TCR and MR1, has been shown to allow for species-mismatched reactivities unique in T cell biology, thereby allowing the use of selected species-mismatched MR1-antigen (MR1-Ag) tetramers in comparative immunology studies. However, the pattern of cross-reactivity of species-mismatched MR1-Ag tetramers in identifying MAIT cells in diverse species has not been formally assessed. We developed novel cattle and pig MR1-Ag tetramers and utilized these alongside previously developed human, mouse, and pig-tailed macaque MR1-Ag tetramers to characterize cross-species tetramer reactivities. MR1-Ag tetramers from each species identified T cell populations in distantly related species with specificity that was comparable to species-matched MR1-Ag tetramers. However, there were subtle differences in staining characteristics with practical implications for the accurate identification of MAIT cells. Pig MR1 is sufficiently conserved across species that pig MR1-Ag tetramers identified MAIT cells from the other species. However, MAIT cells in pigs were at the limits of phenotypic detection. In the absence of sheep MR1-Ag tetramers, a MAIT cell population in sheep blood was identified phenotypically, utilizing species-mismatched MR1-Ag tetramers. Collectively, our results validate the use and define the limitations of species-mismatched MR1-Ag tetramers in comparative immunology studies.

A comparative analysis of TCR immune repertoire in COVID-19 patients.

The coronavirus disease 2019 (COVID-19) has merged as a global health threat since its outbreak in December 2019. Despite widespread recognition, there has been a paucity of studies focusing on the T cell receptor (TCR) bias in adaptive immunity induced by SARS-CoV-2. This research conducted a comparative analysis of the TCR immune repertoire to identify notable αß TCR bias sequences associated with the SARS-CoV-2 virus antigen. The present study encompassed 73 symptomatic COVID-19 patients, categorized as moderate/mild or severe/critical, along with 9 healthy controls. Our findings revealed specific TCR chains prominently utilized by moderate and severe patients, identified as TRAV30-J34-TRBV3-1-J2-7 and TRAV12-3-J6-TRBV28-J1-1, respectively. Additionally, our research explored critical TCR preferences in the bronchoalveolar lavage fluid (BALF) of COVID-19 patients at various disease stages. Indeed, monitoring the dynamics of immune repertoire changes in COVID-19 patients could serve as a crucial biomarker for predicting disease progression and recovery. Furthermore, the study explored TCR bias in both peripheral blood mononuclear cells (PBMCs) and BALF. The most common αß VJ pair observed in BALF was TRAV12-3-J18-TRBV7-6-J2-7. In addition, a comparative analysis with the VDJdb database indicated that the HLA-A*02:01 allele exhibited the widest distribution and highest frequency in COVID-19 patients across different periods. This comprehensive examination provided a global characterization of the TCR immune repertoire in COVID-19 patients, contributing significantly to our understanding of TCR bias induced by SARS-CoV-2.

TRBC1-targeting antibody-drug conjugates for the treatment of T cell cancers.

Antibody and chimeric antigen receptor (CAR) T cell-mediated targeted therapies have improved survival in patients with solid and haematologic malignancies1-9. Adults with T cell leukaemias and lymphomas, collectively called T cell cancers, have short survival10,11 and lack such targeted therapies. Thus, T cell cancers particularly warrant the development of CAR T cells and antibodies to improve patient outcomes. Preclinical studies showed that targeting T cell receptor ß-chain constant region 1 (TRBC1) can kill cancerous T cells while preserving sufficient healthy T cells to maintain immunity12, making TRBC1 an attractive target to treat T cell cancers. However, the first-in-human clinical trial of anti-TRBC1 CAR T cells reported a low response rate and unexplained loss of anti-TRBC1 CAR T cells13,14. Here we demonstrate that CAR T cells are lost due to killing by the patient's normal T cells, reducing their efficacy. To circumvent this issue, we developed an antibody-drug conjugate that could kill TRBC1+ cancer cells in vitro and cure human T cell cancers in mouse models. The anti-TRBC1 antibody-drug conjugate may provide an optimal format for TRBC1 targeting and produce superior responses in patients with T cell cancers.

Virus-Associated CD8+ T-Cells Are Not Activated Through Antigen-Mediated Interaction Inside Atherosclerotic Lesions.

INTRODUCTION: Viral infections have been associated with the progression of atherosclerosis and CD8+ T-cells directed against common viruses, such as influenza, Epstein-Barr virus, and cytomegalovirus, have been detected inside human atherosclerotic lesions. These virus-specific CD8+ T-cells have been hypothesized to contribute to the development of atherosclerosis; however, whether they affect disease progression directly remains unclear. In this study, we aimed to characterize the activation status of virus-specific CD8+ T-cells in the atherosclerotic lesion. METHODS: The presence, clonality, tissue enrichment, and phenotype of virus-associated CD8+ T-cells in atherosclerotic lesions were assessed by exploiting bulk T-cell receptor-ß sequencing and single-cell T-cell receptor (α and ß) sequencing datasets on human endarterectomy samples and patient-matched blood samples. To investigate if virus-specific CD8+ T-cells can be activated through T-cell receptor stimulation in the atherosclerotic lesion, the immunopeptidome of human plaques was determined. RESULTS: Virus-associated CD8+ T-cells accumulated more in the atherosclerotic lesion (mean=2.0%), compared with patient-matched blood samples (mean=1.4%; P=0.05), and were more clonally expanded and tissue enriched in the atherosclerotic lesion in comparison with nonassociated CD8+ T-cells from the lesion. Single-cell T-cell receptor sequencing and flow cytometry revealed that these virus-associated CD8+ T-cells were phenotypically highly similar to other CD8+ T-cells in the lesion and that both exhibited a more activated phenotype compared with circulating T-cells. Interestingly, virus-associated CD8+ T-cells are unlikely to be activated through antigen-specific interactions in the atherosclerotic lesion, as no virus-derived peptides were detected on HLA-I in the lesion. CONCLUSIONS: This study suggests that virus-specific CD8+ T-cells are tissue enriched in atherosclerotic lesions; however, their potential contribution to inflammation may involve antigen-independent mechanisms.

Patient-Specific Targeting of the T-Cell Receptor Variable Region as a Therapeutic Strategy in Clonal T-Cell Diseases.

PURPOSE: Targeted therapeutics are a goal of medicine. Methods for targeting T-cell lymphoma lack specificity for the malignant cell, leading to elimination of healthy cells. The T-cell receptor (TCR) is designed for antigen recognition. T-cell malignancies expand from a single clone that expresses one of 48 TCR variable beta (Vß) genes, providing a distinct therapeutic target. We hypothesized that a mAb that is exclusive to a specific Vß would eliminate the malignant clone while having minimal effects on healthy T cells. EXPERIMENTAL DESIGN: We identified a patient with large granular T-cell leukemia and sequenced his circulating T-cell population, 95% of which expressed Vß13.3. We developed a panel of anti-Vß13.3 antibodies to test for binding and elimination of the malignant T-cell clone. RESULTS: Therapeutic antibody candidates bound the malignant clone with high affinity. Antibodies killed engineered cell lines expressing the patient TCR Vß13.3 by antibody-dependent cellular cytotoxicity and TCR-mediated activation-induced cell death, and exhibited specific killing of patient malignant T cells in combination with exogenous natural killer cells. EL4 cells expressing the patient's TCR Vß13.3 were also killed by antibody administration in an in vivo murine model. CONCLUSIONS: This approach serves as an outline for development of therapeutics that can treat clonal T-cell-based malignancies and potentially other T-cell-mediated diseases. See related commentary by Varma and Diefenbach, p. 4024.

Analysis of thymic generation of shared T-cell receptor α repertoire associated with recognition of tumor antigens shows no preference for neoantigens over wild-type antigens.

BACKGROUND: The number of mutations in cancer cells is an important predictor of a positive response to cancer immunotherapy. It has been suggested that the neoantigens produced by these mutations are more immunogenic than nonmutated tumor antigens, which are likely to be protected by immunological tolerance. However, the mechanisms of tolerance as regards tumor antigens are incompletely understood. METHODS: Here, we have analyzed the impact of thymic negative selection on shared T-cell receptor (TCR) repertoire associated with the recognition of either mutated or nonmutated tumor antigens by comparing previously known TCR-antigen-pairs to TCR repertoires of 21 immunologically healthy individuals. RESULTS: Our results show that TCRα chains associated with either type of tumor antigens are readily generated in the thymus, at a frequency similar to TCRα chains associated with nonself. In the peripheral repertoire, the relative clone size of nonself-associated chains is higher than that of the tumor antigens, but importantly, there is no difference between TCRα chains associated with mutated or nonmutated tumor antigens. CONCLUSION: This suggests that the tolerance mechanisms protecting nonmutated tumor antigens are non-deletional and therefore potentially reversible. As unmutated antigens are, unlike mutations, shared by a large number of patients, they may offer advantages in designing immunological approaches to cancer treatment.

Peptide Centric Vß Specific Germline Contacts Shape a Specialist T Cell Response.

Certain CD8 T cell responses are particularly effective at controlling infection, as exemplified by elite control of HIV in individuals harboring HLA-B57. To understand the structural features that contribute to CD8 T cell elite control, we focused on a strongly protective CD8 T cell response directed against a parasite-derived peptide (HF10) presented by an atypical MHC-I molecule, H-2Ld. This response exhibits a focused TCR repertoire dominated by Vß2, and a representative TCR (TG6) in complex with Ld-HF10 reveals an unusual structure in which both MHC and TCR contribute extensively to peptide specificity, along with a parallel footprint of TCR on its pMHC ligand. The parallel footprint is a common feature of Vß2-containing TCRs and correlates with an unusual Vα-Vß interface, CDR loop conformations, and Vß2-specific germline contacts with peptides. Vß2 and Ld may represent "specialist" components for antigen recognition that allows for particularly strong and focused T cell responses.

Serial Analysis of the T-Cell Receptor ß-Chain Repertoire in People Living With HIV Reveals Incomplete Recovery After Long-Term Antiretroviral Therapy.

Long-term antiretroviral therapy (ART) in people living with HIV (PLHIV) is associated with sustained increases in CD4+ T-cell count, but its effect on the peripheral blood T-cell repertoire has not been comprehensively evaluated. In this study, we performed serial profiling of the composition and diversity of the T-cell receptor ß-chain (TRB) repertoire in 30 adults with HIV infection before and after the initiation of ART to define its long-term impact on the TRB repertoire. Serially acquired blood samples from 30 adults with HIV infection collected over a mean of 6 years (range, 1-12) years, with 1-4 samples collected before and 2-8 samples collected after the initiation of ART, were available for analysis. TRB repertoires were characterized via high-throughput sequencing of the TRB variable region performed on genomic DNA extracted from unsorted peripheral blood mononuclear cells. Additional laboratory and clinical metadata including serial measurements of HIV viral load and CD4 + T-cell count were available for all individuals in the cohort. A previously published control group of 189 TRB repertoires from peripheral blood samples of adult bone marrow transplant donors was evaluated for comparison. ART initiation in PLHIV was associated with a sustained reduction in viral load and a significant increase in TRB repertoire diversity. However, repertoire diversity in PLHIV remained significantly lower than in the control group even after long-term ART. The composition of TRB repertoires of PLHIV after ART also remained perturbed compared to the control cohort, as evidenced by large persistent private clonal expansions, reduced efficiency in the generation of TRB CDR3 amino acid sequences, and a narrower range of CDR3 lengths. Network analysis revealed an antigen-experienced structure in the TRB repertoire of PLHIV both before and after ART initiation that was quite distinct from the structure of control repertoires, with a slight shift toward a more naïve structure observed after ART initiation. Though we observe significant improvement in TRB repertoire diversity with durable viral suppression in PLHIV on long-term ART, the composition and structure of these repertoires remain significantly perturbed compared to the control cohort of adult bone marrow transplant donors.

Computational discovery of binding mode of anti-TRBC1 antibody and predicted key amino acids of TRBC1.

Peripheral T-cell lymphoma (PTCL) is a type of non-Hodgkin lymphoma that progresses aggressively with poor survival rate. CAR T cell targeting T-cell receptor ß-chain constant domains 1 (TRBC1) of malignant T cells has been developed recently by using JOVI.1 monoclonal antibody as a template. However, the mode of JOVI.1 binding is still unknown. This study aimed to investigate the molecular interaction between JOVI.1 antibody and TRBC1 by using computational methods and molecular docking. Therefore, the TRBC protein crystal structures (TRBC1 and TRBC2) as well as the sequences of JOVI.1 CDR were chosen as the starting materials. TRBC1 and TRBC2 epitopes were predicted, and molecular dynamic (MD) simulation was used to visualize the protein dynamic behavior. The structure of JOVI.1 antibody was also generated before the binding mode was predicted using molecular docking with an antibody mode. Epitope prediction suggested that the N3K4 region of TRBC1 may be a key to distinguish TRBC1 from TCBC2. MD simulation showed the major different surface conformation in this area between two TRBCs. The JOVI.1-TRBC1 structures with three binding modes demonstrated JOVI.1 interacted TRBC1 at N3K4 residues, with the predicted dissociation constant (Kd) ranging from 1.5 × 108 to 1.1 × 1010 M. The analysis demonstrated JOVI.1 needed D1 residues of TRBC1 for the interaction formation to N3K4 in all binding modes. In conclusion, we proposed the three binding modes of the JOVI.1 antibody to TRBC1 with the new key residue (D1) necessary for N3K4 interaction. This data was useful for JOVI.1 redesign to improve the PTCL-targeting CAR T cell.

Advanced Glycation End-Products (AGEs) of Lysine and Effects of Anti-TCR/Anti-TNF-α Antibody-Based Therapy in the LEW.1AR1-iddm Rat, an Animal Model of Human Type 1 Diabetes.

The LEW.1AR1-iddm rat is an animal model of human type 1 diabetes (T1D). Previously, we have shown that combination with anti-TCR/anti-TNF-α antibody-based therapy re-established normoglycemia and increased proteinic arginine-dimethylation in the spleen, yet not in the pancreas. High blood glucose is often associated with elevated formation of advanced glycation end-products (AGEs) which act via their receptor (RAGE). Both anti-TCR and anti-TNF-α are inhibitors of RAGE. The aim of the present work was to investigate potential biochemical changes of anti-TCR/anti-TNF-α therapy in the LEW.1AR1-iddm rat. We determined by stable-isotope dilution gas chromatography-mass spectrometry (GC-MS) the content of free and proteinic AGEs and the Nε-monomethylation of lysine (Lys) residues in proteins of pancreas, kidney, liver, spleen and lymph nodes of normoglycemic control (ngCo, n = 6), acute diabetic (acT1D, n = 6), chronic diabetic (chT1D, n = 4), and cured (cuT1D, n = 4) rats after anti-TCR/anti-TNF-α therapy. Analyzed biomarkers included Lys and its metabolites Nε-carboxymethyl lysine (CML), furosine and Nε-monomethyl lysine (MML). Other amino acids were also determined. Statistical methods including ANOVA, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to evaluate the effects. Most statistical differences between the study groups were observed for spleen, pancreas and kidney, with liver and lymph nodes showing no such differences. In the pancreas, the groups differed with respect to proteinic furosine (p = 0.0289) and free CML (p = 0.0023). In the kidneys, the groups differed with respect to proteinic furosine (p = 0.0076) and CML (p = 0.0270). In the spleen, group differences were found for proteinic furosine (p = 0.0114) and free furosine (p = 0.0368), as well as for proteinic CML (p = 0.0502) and proteinic MML (p = 0.0191). The acT1D rats had lower furosine, CML and MML levels in the spleen than the rats in all other groups. This observation corresponds to the lower citrullination levels previously measured in these rats. PCA revealed diametric associations between PC1 and PC2 for spleen (r = -0.8271, p < 0.0001) compared to pancreas (r = 0.5805, p = 0.0073) and kidney (r = 0.8692, p < 0.0001). These findings underscore the importance of the spleen in this animal model of human T1D. OPLS-DA showed that in total sixteen amino acids differed in the experimental groups.

TRB sequences targeting ORF1a/b are associated with disease severity in hospitalized COVID-19 patients.

The potential protective or pathogenic role of the adaptive immune response to SARS-CoV-2 infection has been vigorously debated. While COVID-19 patients consistently generate a T lymphocyte response to SARS-CoV-2 antigens, evidence of significant immune dysregulation in these patients continues to accumulate. In this study, next generation sequencing of the T cell receptor beta chain (TRB) repertoire was conducted in hospitalized COVID-19 patients to determine if immunogenetic differences of the TRB repertoire contribute to disease course severity. Clustering of highly similar TRB CDR3 amino acid sequences across COVID-19 patients yielded 781 shared TRB sequences. The TRB sequences were then filtered for known associations with common diseases such as EBV and CMV. The remaining sequences were cross-referenced to a publicly accessible dataset that mapped COVID-19 specific TCRs to the SARS-CoV-2 genome. We identified 158 SARS-CoV-2 specific TRB sequences belonging to 134 clusters in our COVID-19 patients. Next, we investigated 113 SARS-CoV-2 specific clusters binding only one peptide target in relation to disease course. Distinct skewing of SARS-CoV-2 specific TRB sequences toward the nonstructural proteins (NSPs) encoded within ORF1a/b of the SARS-CoV-2 genome was observed in clusters associated with critical disease course when compared to COVID-19 clusters associated with a severe disease course. These data imply that T-lymphocyte reactivity towards peptides from NSPs of SARS-CoV-2 may not constitute an effective adaptive immune response and thus may negatively affect disease severity.

An efficient single-cell based method for linking human T cell phenotype to T cell receptor sequence and specificity.

Single-cell antigen-receptor gene amplification and sequencing platforms have been used to characterize T cell receptor (TCR) repertoires but typically fail to generate paired full-length gene products for direct expression cloning and do not enable linking this data to cell phenotype information. To overcome these limitations, we established a high-throughput platform for the quantitative and qualitative analysis of human TCR repertoires that provides insights into the clonal and functional composition of human CD4+ and CD8+ αß T cells at the molecular and cellular level. The strategy is a powerful tool to qualitatively assess differences between antigen receptors of phenotypically defined αß T cell subsets, e.g. in immune responses to cancer, vaccination, or infection, and in autoimmune diseases.

Allelic variation in class I HLA determines CD8+ T cell repertoire shape and cross-reactive memory responses to SARS-CoV-2.

Effective presentation of antigens by human leukocyte antigen (HLA) class I molecules to CD8+ T cells is required for viral elimination and generation of long-term immunological memory. In this study, we applied a single-cell, multiomic technology to generate a unified ex vivo characterization of the CD8+ T cell response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) across four major HLA class I alleles. We found that HLA genotype conditions key features of epitope specificity, TCRα/ß sequence diversity, and the utilization of pre-existing SARS-CoV-2-reactive memory T cell pools. Single-cell transcriptomics revealed functionally diverse T cell phenotypes of SARS-CoV-2-reactive T cells, associated with both disease stage and epitope specificity. Our results show that HLA variations notably influence the CD8+ T cell repertoire shape and utilization of immune recall upon SARS-CoV-2 infection.

Peanut oral immunotherapy differentially suppresses clonally distinct subsets of T helper cells.

Food allergy affects an estimated 8% of children in the United States. Oral immunotherapy (OIT) is a recently approved treatment, with outcomes ranging from sustained tolerance to food allergens to no apparent benefit. The immunological underpinnings that influence clinical outcomes of OIT remain largely unresolved. Using single-cell RNA-Seq and paired T cell receptor α/ß (TCRα/ß) sequencing, we assessed the transcriptomes of CD154+ and CD137+ peanut-reactive T helper (Th) cells from 12 patients with peanut allergy longitudinally throughout OIT. We observed expanded populations of cells expressing Th1, Th2, and Th17 signatures that further separated into 6 clonally distinct subsets. Four of these subsets demonstrated a convergence of TCR sequences, suggesting antigen-driven T cell fates. Over the course of OIT, we observed suppression of Th2 and Th1 gene signatures in effector clonotypes but not T follicular helper-like (Tfh-like) clonotypes. Positive outcomes were associated with stronger suppression of Th2 signatures in Th2A-like cells, while treatment failure was associated with the expression of baseline inflammatory gene signatures that were present in Th1 and Th17 cell populations and unmodulated by OIT. These results demonstrate that differential clinical responses to OIT are associated with both preexisting characteristics of peanut-reactive CD4+ T cells and suppression of a subset of Th2 cells.

[Development of allogeneic CAR T-cells]. / Développement des CAR-T allogéniques.

Chimeric antigen receptor (CAR) T-cell therapy represents a major breakthrough in the field of hematology. "Off-the-shelf" allogeneic CAR T-cells from donors have many potential advantages over autologous approaches, such as the immediate availability of cryopreserved batches, possible standardization of the cell product, time for multiple cell modifications, redosing and decreased cost. However, allogeneic T-cells possess foreign immunological identities that can lead to graft-versus-host disease (GvHD) and their rejection by the host immune system. In this review, we describe the different approaches to produce allogeneic CAR T-cells with limited potential for GvHD and that can persist in the recipient. The preliminary clinical results obtained with the first generation of allogeneic CAR T-cells are presented as well as the perspectives in hematological malignancies and solid tumors.