The Croonian Lecture, 1992. The key role of the thymus in the body’s defence strategies

1992 ◽  
Vol 337 (1279) ◽  
pp. 105-124 ◽  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Bone Marrow Cells ◽  
Cell Receptor ◽  
Division Of Labour ◽  
T Cell Subsets ◽  
Lymphoid Tissues ◽  
Cell Repertoire ◽  
Long Time ◽  
T Cell Selection

For centuries the thymus has remained a mysterious organ with largely unknown functions. The first demonstration of its crucial role in the development of the immune system was reported in 1961, when it was found that mice thymectomized at birth had poorly developed lymphoid tissues, impaired immune reactivities, and an inordinate susceptibility to develop infections. Although thymus lymphocytes were for a long time deemed immunoincompetent, it was shown in 1967 that they could respond to antigen by proliferating to give rise to a progeny of cells which did not secrete antibody (T cells), but which had a remarkable ability to induce bone marrow cells (B cells) to become antibody formers. This was the first unequivocal demonstration of a major division of labour among mammalian lymphocytes. Tremendous progress in our understanding of the function of the thymus and of the T cells derived from it followed. Distinct T cell subsets were characterized and shown to have an essential role in initiating and regulating a variety of immune responses. The ontogenetic events which occurred during their differentiation were mapped, and this allowed studies of the selection of the T cell repertoire. The major histocompatibility complex and associated peptides were shown to govern T cell selection and antigen activation, and the antigen-specific T cell receptor and the genes which code for it were characterized. Future studies should allow some insight into how to activate T cells more effectively for vaccination purposes, and how to switch them off to prevent autoimmune reactions and to induce tolerance to transplanted tissues.

Analysis of the Human T Cell Receptor (TCR) Repertoire from Birth to Old Age Suggests That TCRVβfrequencies Are Established Independent of HLA.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3313-3313
Author(s):  
J. Joseph Melenhorst ◽  
Josette Zeilah ◽  
Edgardo Sosa ◽  
Dean Follmann ◽  
Nancy F. Hensel ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Protein Expression ◽  
Rank Order ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
Rank Test ◽  
Cell Repertoire ◽  
Cd8 Cells ◽  
Human T Cell

Abstract Human T cell development occurs in two waves of development and proliferation: first, early T cells expressing the TCRb chain but not the α-chain are selected for functional TCRβ protein independent of HLA recognition, a process called β-selection; second, thymocytes expressing both the α- and β-TCR are selected for intermediate affinity for self-MHC/ self-peptide complex. This latter process is referred to as positive selection. We sought to determine whether the peripheral TCRVβ frequencies in the naïve T cell repertoire start off at a fixed rank order with minimal skewing as would be expected from a predominantly β-selected repertoire. A total of 22 TCRVβ proteins was quantitated by flow cytometry in a group of 20 unselected umbilical cord blood (UCB) samples (a kind gift from Dr. P. Rubinstein, NY Blood Center, NY), consisting of >80% naïve T cells as defined by CD27+CD45RA+ staining in CD4+ and CD8+ cells. A common rank order of TCRVβ protein frequencies was found in both CD4 and CD8 T cell subsets (figure 1). Median TCRVβ frequencies in CD4 and in CD8 cells of UCB were statistically not significantly different from the frequencies in adult donor CD4 and CD8 cells (Wilcoxon signed rank test; p > 0.2). Furthermore, the percentages of CD4 cells expressing a particular Vβ correlated significantly in CD8 cells (figure 2) with some Vβ proteins being predominantly expressed by either CD4 (Vβ2, Vβ5.1) or CD8 (Vβ14, Vβ7) cells. Our data therefore conform to the prediction that the TCRVβ frequencies are dominantly shaped by β-selection, and not by interactions of the αβTCR/ co-receptor with MHC/ antigen complexes during thymic selection. Figure 1. TCRBV in UCB CD4+ (top) and CD8+ (bottom) T cells Figure 1. TCRBV in UCB CD4+ (top) and CD8+ (bottom) T cells Figure 2. Comparison of TCRBV protein expression frequencies in CD4 and CD8 cells of UCB Figure 2. Comparison of TCRBV protein expression frequencies in CD4 and CD8 cells of UCB

scholarly journals Development of a CD8 co-receptor independent T-cell receptor specific for tumor-associated antigen MAGE-A4 for next generation T-cell-based immunotherapy

2021 ◽  
Vol 9 (3) ◽  
pp. e002035
Author(s):  
Kathrin Davari ◽  
Tristan Holland ◽  
Laura Prassmayer ◽  
Giulia Longinotti ◽  
Kenneth P Ganley ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
In Vivo Studies ◽  
High Avidity ◽  
Cell Repertoire

BackgroundThe cancer-testis antigen MAGE-A4 is an attractive target for T-cell-based immunotherapy, especially for indications with unmet clinical need like non-small cell lung or triple-negative breast cancer.MethodsAn unbiased CD137-based sorting approach was first used to identify an immunogenic MAGE-A4-derived epitope (GVYDGREHTV) that was properly processed and presented on human leukocyte antigen (HLA)-A2 molecules encoded by the HLA-A*02:01 allele. To isolate high-avidity T cells via subsequent multimer sorting, an in vitro priming approach using HLA-A2-negative donors was conducted to bypass central tolerance to this self-antigen. Pre-clinical parameters of safety and activity were assessed in a comprehensive set of in vitro and in vivo studies.ResultsA MAGE-A4-reactive, HLA-A2-restricted T-cell receptor (TCR) was isolated from primed T cells of an HLA-A2-negative donor. The respective TCR-T-cell (TCR-T) product bbT485 was demonstrated pre-clinically to have a favorable safety profile and superior in vivo potency compared with TCR-Ts expressing a TCR derived from a tolerized T-cell repertoire to self-antigens. This natural high-avidity TCR was found to be CD8 co-receptor independent, allowing effector functions to be elicited in transgenic CD4+ T helper cells. These CD4+ TCR-Ts supported an anti-tumor response by direct killing of MAGE-A4-positive tumor cells and upregulated hallmarks associated with helper function, such as CD154 expression and release of key cytokines on tumor-specific stimulation.ConclusionThe extensive pre-clinical assessment of safety and in vivo potency of bbT485 provide the basis for its use in TCR-T immunotherapy studies. The ability of this non-mutated high-avidity, co-receptor-independent TCR to activate CD8+ and CD4+ T cells could potentially provide enhanced cellular responses in the clinical setting through the induction of functionally diverse T-cell subsets that goes beyond what is currently tested in the clinic.

Functional and Numerical T Cell Abnormalities in Chronic Lymphocytic Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3085-3085
Author(s):  
Mark C. Lanasa ◽  
Marc C. Levesque ◽  
Sallie D. Allgood ◽  
Jon P. Gockerman ◽  
Karen Bond ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Unequal Variances

Abstract Background: Although most malignancies are associated with decreased numbers of circulating T cells, in CLL they are elevated 2 to 4 times normal. Rather than promoting an anti-tumor response, this increased population of T cells may contribute to a tumor microenvironment that fosters progression of the malignant clone. Immunocompetent individuals show a wide repertoire of antigen specificity in both CD4+ and CD8+ T cells, but the T cell repertoire is significantly restricted in CLL. This restriction of the T cell repertoire may be an important cause of infectious morbidity in patients with CLL. To better understand these T cell abnormalities, we enumerated T cell subsets and determined T cell receptor diversity in 18 untreated patients with CLL. Methods: T cell subsets were enumerated from peripheral blood using highly sensitive 6-color flow cytometry. The T cell repertoire was determined for 23 T cell receptor variable β chain families (TCRvβ) in purified CD4+ and CD8+ T cells. These T cell subsets were considered separately because differential restriction of the CD4+ and CD8+ subsets has been reported previously. A PCR-based spectratype assay was used to analyze the length distribution of the TCR complementarity-determining region 3 (CDR3). A limitation of prior reports using spectratype assays was that adequately complex statistical models did not exist to simultaneously analyze the highly diverse vβ families. We addressed this limitation by using a recently-developed statistical method for spectratype analysis (Bioinformatics. 21:3394–400). Briefly, for each vβ family, the divergence from an expected reference distribution was calculated. A divergence coefficient was determined for each vβ family, and the mean divergence of all 23 vβ families was calculated. This allowed for statistical comparisons among individual patients and specific vβ families. To our knowledge, we are the first group to apply this powerful methodology to the analysis of T cell repertoires in patients with CLL. Results: We found both the CD4+ and CD8+ subsets to be expanded (mean #/μL ± SD: 1134 ± 646 and 768 ± 716, respectively; reference normal CD4+ range 401–1532, CD8+ 152–838). The absolute number of CD4+ and CD8+ T cells was greater in patients with higher absolute CLL lymphocyte counts (p = 0.018, r2 = 0.30, and p = 0.23, r2 = 0.09, respectively, linear regression). The CD4:CD8 ratio was lower in IgVH unmutated subjects (mutated 2.6, umutated 1.7, p = 0.09, two-tailed t-test assuming unequal variances). Though prior reports have disagreed on whether CD4+ or CD8+ subsets show greater restriction of clonality, we observed striking clonal restriction of CD8+ but not CD4+ T cells (p < 1×10−7, 2 sided t-test assuming unequal variances). There was a trend toward greater restriction of the CD8+ subset among patients with IgVH unmutated and Zap70+ CLL, but there was no correlation with lymphocyte doubling time. Conclusions: In this cohort of 18 untreated patients with CLL, there was a greater proportional increase compared to reference standards of CD8+ versus CD4+ T cells. However, the increase in CD4+, but not CD8+, T cell numbers was significantly correlated to total CLL lymphocyte count. This observation suggests that expansion of the CD4+ T cell pool observed in CLL is proportional to leukemic burden. The restriction of TCRvβ was limited to CD8+ T cells and that this effect was independent of the size of the abnormal clone. Taken together, these findings suggest different mechanisms of dysregulation of CD4+ and CD8+ T cell subsets in CLL.

scholarly journals Acquired Mls-1a-like clonal deletion in Mls-1b mice.

1992 ◽  
Vol 175 (2) ◽  
pp. 453-460 ◽  
Author(s):  
M Papiernik ◽  
C Pontoux ◽  
S Gisselbrecht
Keyword(s):  
T Cells ◽  
T Cell ◽  
Bone Marrow Cells ◽  
Cell Receptor ◽  
Cell Repertoire ◽  
Clonal Deletion ◽  
Genetic Transmission ◽  
Cd8 Cells ◽  
High Level

BALB/c mice (H-2d, Mls-1b) from one colony progressively modify their T cell repertoire during aging, by deleting T cells that express products of the V beta 6 and V beta 8.1 genes of the T cell receptor. Clonal deletion occurs only in 50% of mice between 27 and 43 wk of age, affecting thymus, spleen, and lymph node T cells. The phenomenon is progressive and seems to affect nearly all thymuses between 14 and 19 wk of age. CD4+CD8- mature T cells are more affected than CD4-CD8+ cells. In the thymus, deletion occurs at the stage of immature J11d+ cells expressing a high level of V beta 6, while J11d+V beta 6low-expressing cells are not modified. Clonal deletion is thus an early phenomenon that deletes cells of the immature generative compartment in the thymus. This Mls-1a-like clonal deletion is associated neither with the expression of an Mls-1a-like antigen that could be identified in mixed lymphocyte reaction in vitro, nor with the presence of Mtv-7, the endogenous mouse mammary tumor virus (MMTV) proviral loci. Spleen cells, bone marrow cells, and total thymocytes injected into newborn thymuses cannot induce V beta 6+ cell deletion. However, newborn thymuses grafted into old BALB/c mice behave like their recipients, suggesting that a new antigen, present in these old BALB/c mice, is indeed able to induce an Mls-1a-like clonal deletion. As other BALB/c colonies tested do not behave in same way, the hypothesis of a new exogenous deleting factor rather than a genetic transmission is likely. This may suggest that acquired clonal deletion is a more common phenomenon than expected, and may be the spontaneous reaction of the immune system to the introduction of a new retrovirus or other superantigen.

scholarly journals Comprehensive analysis of structural and sequencing data reveals almost unconstrained chain pairing in TCRαβ complex

2019 ◽  
Author(s):  
Dmitrii S Shcherbinin ◽  
Vlad A Belousov ◽  
Mikhail Shugay
Keyword(s):  
T Cells ◽  
T Cell ◽  
Structural Data ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
Sequencing Data ◽  
Antigen Specificity ◽  
Cell Repertoire ◽  
Effective Response ◽  
Specific Choice

AbstractAntigen recognition by T-cells is guided by the T-cell receptor (TCR) heterodimer formed by α and β chains. A huge diversity of TCR sequences should be maintained by the immune system in order to be able to mount an effective response towards foreign pathogens, so, due to cooperative binding of α and β chains to the pathogen, any constraints on chain pairing can have a profound effect on immune repertoire structure, diversity and antigen specificity. By integrating available structural data and paired chain sequencing results we were able to show that there are almost no constraints on pairing in TCRαβ complexes, allowing naive T-cell repertoire to reach the highest possible diversity. Additional analysis reveals that the specific choice of contacting amino acids can still have a profound effect on complex conformation. Moreover, antigen-driven selection can distort the uniform landscape of chain pairing, while small, yet significant, differences in the pairing can be attributed to various specialized T-cell subsets such as MAIT and iNKT T-cells, as well as other putative invariant TCRs.

scholarly journals Characterization of Changes in the T-Cell Receptor Repertoire in Patients with Acute Myeloid Leukemia with Durable Remission Following Allogeneic Stem Cell Transplant

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5186-5186
Author(s):  
Ronald M. Paranal ◽  
Hagop M. Kantarjian ◽  
Alexandre Reuben ◽  
Celine Kerros ◽  
Priya Koppikar ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Cell Receptor ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Donor T Cells ◽  
Durable Remission

Introduction: Allogeneic hematopoietic stem-cell transplantation (HSCT) is curative for many patients with advanced hematologic cancers, including adverse-risk acute myeloid leukemia (AML). This is principally through the induction of a graft-versus-leukemia (GVL) immune effect, mediated by donor T-cells. The incredible diversity and specificity of T-cells is due to rearrangement between V, D, and J regions and the random insertion/deletion of nucleotides, taking place in the hypervariable complementarity determining region 3 (CD3) of the T-cell receptor (TCR). Massively parallel sequencing of CDR3 allows for a detailed understanding of the T-cell repertoire, an area relatively unexplored in AML. Therefore, we sought out to characterize the T-cell repertoire in AML before and after HSCT, specifically for those with a durable remission. Methods: We identified 45 bone marrow biopsy samples, paired pre- and post-HSCT, from 14 patients with AML in remission for > 2 years as of last follow-up. We next performed immunosequencing of the TCRβ repertoire (Adaptive Biotechnologies). DNA was amplified in a bias-controlled multiplex PCR, resulting in amplification of rearranged VDJ segments, followed by high-throughput sequencing. Resultant sequences were collapsed and filtered in order to identify and quantitate the absolute abundance of each unique TCRβ CDR3 region. We next employed various metrics to characterize changes in the TCR repertoire: (1) clonality (range: 0-1; values closer to 1 indicate a more oligoclonal repertoire), it accounts for both the number of unique clonotypes and the extent to which a few clonotypes dominate the repertoire; (2) richness with a higher number indicating a more diverse repertoire with more unique rearrangements); (3) overlap (range: 0-1; with 1 being an identical T-cell repertoire). All calculations were done using the ImmunoSeq Analyzer software. Results: The median age of patients included in this cohort was 58 years (range: 31-69). Six patient (43%) had a matched related donor, and 8 (57%) had a matched unrelated donor. Baseline characteristics are summarized in Figure 1A. Six samples were excluded from further analysis due to quality. TCR richness did not differ comparing pre- and post-HSCT, with a median number pre-HSCT of 3566 unique sequences (range: 1282-22509) vs 3720 (range: 1540-12879) post-HSCT (P = 0.7). In order to assess whether there was expansion of certain T-cell clones following HSCT, we employed several metrics and all were indicative of an increase in clonality (Figure 2B). Productive clonality, a measure of reactivity, was significantly higher in post-transplant samples (0.09 vs 0.02, P = 0.003). This is a measure that would predict expansion of sequences likely to produce functional TCRs. The Maximum Productive Frequency Index was higher post-HSCT indicating that the increase in clonality was driven by the top clone (most prevalent per sample). Similarly for the Simpson's Dominance index, another marker of clonality which was higher post-HSCT (0.01 vs 0.0009, P = 0.04). In order to determine whether this clonal expansion was driven by TCR clones shared among patients, we compared the degree of overlap in unique sequences among pre and post-HSCT samples. We found there was very little overlap between samples in the pre and the post-transplant setting and no change in the Morisita and Jaccard Overlap Indices. Conclusions: In conclusion, we show in this analysis an increase in clonality of T-cells following HSCT in patients with AML. This is likely related to the GVL effect after recognition of leukemia antigens by donor T cells and subsequent expansion of these T-cells. These expanded T-cell clonotypes were unlikely to be shared by patients in this cohort, likely reflecting the variety of antigens leading to the GVL effect. This could have direct implications on TCR-mediated immune-therapies given the likely need for a personalized, patient-specific design for these therapies. Figure 1 Disclosures Kantarjian: BMS: Research Funding; Novartis: Research Funding; AbbVie: Honoraria, Research Funding; Jazz Pharma: Research Funding; Astex: Research Funding; Immunogen: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; Takeda: Honoraria; Amgen: Honoraria, Research Funding; Cyclacel: Research Funding; Ariad: Research Funding; Pfizer: Honoraria, Research Funding. Short:Takeda Oncology: Consultancy, Research Funding; AstraZeneca: Consultancy; Amgen: Honoraria. Cortes:Takeda: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Sun Pharma: Research Funding; BiolineRx: Consultancy; Novartis: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; Merus: Consultancy, Honoraria, Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Biopath Holdings: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Forma Therapeutics: Consultancy, Honoraria, Research Funding. Jabbour:Cyclacel LTD: Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Adaptive: Consultancy, Research Funding. Molldrem:M. D. Anderson & Astellas Pharma: Other: Royalties.

scholarly journals Naïve Regulatory T Cell Subset Is Altered in X-Linked Agammaglobulinemia

2021 ◽  
Vol 12 ◽  
Author(s):  
Pavel V. Shelyakin ◽  
Ksenia R. Lupyr ◽  
Evgeny S. Egorov ◽  
Ilya A. Kofiadi ◽  
Dmitriy B. Staroverov ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Cell Subset ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
Cell Compartments ◽  
Expression Of Genes ◽  
Tcr Repertoire ◽  
Antigen Presenting

The interplay between T- and B-cell compartments during naïve, effector and memory T cell maturation is critical for a balanced immune response. Primary B-cell immunodeficiency arising from X-linked agammaglobulinemia (XLA) offers a model to explore B cell impact on T cell subsets, starting from the thymic selection. Here we investigated characteristics of naïve and effector T cell subsets in XLA patients, revealing prominent alterations in the corresponding T-cell receptor (TCR) repertoires. We observed immunosenescence in terms of decreased diversity of naïve CD4+ and CD8+ TCR repertoires in XLA donors. The most substantial alterations were found within naïve CD4+ subsets, and we have investigated these in greater detail. In particular, increased clonality and convergence, along with shorter CDR3 regions, suggested narrower focused antigen-specific maturation of thymus-derived naïve Treg (CD4+CD45RA+CD27+CD25+) in the absence of B cells - normally presenting diverse self and commensal antigens. The naïve Treg proportion among naïve CD4 T cells was decreased in XLA patients, supporting the concept of impaired thymic naïve Treg selection. Furthermore, the naïve Treg subset showed prominent differences at the transcriptome level, including increased expression of genes specific for antigen-presenting and myeloid cells. Altogether, our findings suggest active B cell involvement in CD4 T cell subsets maturation, including B cell-dependent expansion of the naïve Treg TCR repertoire that enables better control of self-reactive T cells.

scholarly journals An invariant V alpha 24-J alpha Q/V beta 11 T cell receptor is expressed in all individuals by clonally expanded CD4-8- T cells.

1994 ◽  
Vol 180 (3) ◽  
pp. 1171-1176 ◽  
Author(s):  
P Dellabona ◽  
E Padovan ◽  
G Casorati ◽  
M Brockhaus ◽  
A Lanzavecchia
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Cell Clone ◽  
Cell Subset ◽  
Cell Receptor ◽  
T Cell Subsets ◽  
T Cell Clone ◽  
Gene Usage ◽  
Beta Gene

The T cell receptor (TCR)-alpha/beta CD4-8- (double negative, DN) T cell subset is characterized by an oligoclonal repertoire and a restricted V gene usage. By immunizing mice with a DN T cell clone we generated two monoclonal antibodies (mAbs) against V alpha 24 and V beta 11, which have been reported to be preferentially expressed in DN T cells. Using these antibodies, we could investigate the expression and pairing of these V alpha and V beta gene products among different T cell subsets. V alpha 24 is rarely expressed among CD4+ and especially CD8+ T cells. In these cases it is rearranged to different J alpha segments, carries N nucleotides, and pairs with different V beta. Remarkably, V alpha 24 is frequently expressed among DN T cells and is always present as an invariant rearrangement with J alpha Q, without N region diversity. This invariant V alpha 24 chain is always paired to V beta 11. This unique V alpha 24-J alpha Q/V beta 11 TCR was found in expanded DN clones from all the individuals tested. These findings suggest that the frequent occurrence of cells carrying this invariant TCR is due to peripheral expansion of rare clones after recognition of a nonpolymorphic ligand.

scholarly journals Diversification of the antigen-specific T cell receptor repertoire after varicella zoster vaccination

2016 ◽  
Vol 8 (332) ◽  
pp. 332ra46-332ra46 ◽  
Author(s):  
Qian Qi ◽  
Mary M. Cavanagh ◽  
Sabine Le Saux ◽  
Hong NamKoong ◽  
Chulwoo Kim ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Chronic Infection ◽  
Cell Receptor ◽  
Control Mechanisms ◽  
Cell Repertoire ◽  
T Cell Clones ◽  
Varicella Zoster ◽  
Cell Clones

Diversity and size of the antigen-specific T cell receptor (TCR) repertoire are two critical determinants for successful control of chronic infection. Varicella zoster virus (VZV) that establishes latency during childhood can escape control mechanisms, in particular with increasing age. We examined the TCR diversity of VZV-reactive CD4 T cells in individuals older than 50 years by studying three identical twin pairs and three unrelated individuals before and after vaccination with live attenuated VZV. Although all individuals had a small number of dominant T cell clones, the breadth of the VZV-specific repertoire differed markedly. A genetic influence was seen for the sharing of individual TCR sequences from antigen-reactive cells but not for repertoire richness or the selection of dominant clones. VZV vaccination favored the expansion of infrequent VZV antigen–reactive TCRs, including those from naïve T cells with lesser boosting of dominant T cell clones. Thus, vaccination does not reinforce the in vivo selection that occurred during chronic infection but leads to a diversification of the VZV-reactive T cell repertoire. However, a single-booster immunization seems insufficient to establish new clonal dominance. Our results suggest that repertoire analysis of antigen-specific TCRs can be an important readout to assess whether a vaccination was able to generate memory cells in clonal sizes that are necessary for immune protection.

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