Reduction Of Immune Repertoire Diversity Through DNA Sequence Constraints At VDJ Junctions

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4944-4944
Author(s):  
Bryan Howie ◽  
Harlan Robins ◽  
Christopher S Carlson

Abstract B and T lymphocytes are effector cells of the adaptive immune system. These cells express surface receptors that bind a huge variety of antigens, and together they comprise a person’s immune repertoire. A diverse repertoire is essential for mounting robust immune responses against a wide range of pathogens, and repertoire diversity affects the probability that DNA sequencing can uniquely tag a clonally expanded population of cells for the detection of minimum residual disease (MRD) during cancer treatment. Immune repertoire diversity arises partly through the combinatorial splicing of gene segments from the variable (V), diversity (D), and joining (J) regions of a B or T cell receptor locus. Much additional diversity is created through the stochastic insertion and deletion of nucleotides at the splice junctions, and by somatic hypermutation (SHM) in maturing lymphocytes. The generation of junctional diversity is an important part of this process, but it may be constrained by the underlying biological mechanisms. To explore the landscape of junctional diversity among immune receptor loci, we developed a likelihood model that can annotate VDJ junctions in the presence of SHM and compute the probability that a given receptor sequence was generated only once in a person’s repertoire, which is essential for tracking MRD. Using high-throughput sequencing data from several individuals and a range of receptor loci, we identify mechanistic constraints that limit B and T cell receptor diversity. For example, we show that the usual variability in CDR3 length is reduced at the immunoglobulin kappa (IgK) locus, and we connect this finding to sequence motifs that constrain nucleotide deletion at the ends of IgK gene segments. Our findings will inform future genetic studies of the adaptive immune system, and they provide quantitative guidance for deciding which cancer clones can be tracked for reliable MRD detection. Disclosures: Howie: Adaptive Biotechnologies: Employment, Equity Ownership. Robins:Adaptive Biotechnologies: Consultancy, Equity Ownership, Patents & Royalties. Carlson:Adaptive Biotechnologies: Consultancy, Equity Ownership, Patents & Royalties.

Blood ◽  
2009 ◽  
Vol 114 (19) ◽  
pp. 4099-4107 ◽  
Author(s):  
Harlan S. Robins ◽  
Paulo V. Campregher ◽  
Santosh K. Srivastava ◽  
Abigail Wacher ◽  
Cameron J. Turtle ◽  
...  

Abstract The adaptive immune system uses several strategies to generate a repertoire of T- and B-cell antigen receptors with sufficient diversity to recognize the universe of potential pathogens. In αβ T cells, which primarily recognize peptide antigens presented by major histocompatibility complex molecules, most of this receptor diversity is contained within the third complementarity-determining region (CDR3) of the T-cell receptor (TCR) α and β chains. Although it has been estimated that the adaptive immune system can generate up to 1016 distinct αβ pairs, direct assessment of TCR CDR3 diversity has not proved amenable to standard capillary electrophoresis-based DNA sequencing. We developed a novel experimental and computational approach to measure TCR CDR3 diversity based on single-molecule DNA sequencing, and used this approach to determine the CDR3 sequence in millions of rearranged TCRβ genes from T cells of 2 adults. We find that total TCRβ receptor diversity is at least 4-fold higher than previous estimates, and the diversity in the subset of CD45RO+ antigen-experienced αβ T cells is at least 10-fold higher than previous estimates. These methods should prove valuable for assessment of αβ T-cell repertoire diversity after hematopoietic cell transplantation, in states of congenital or acquired immunodeficiency, and during normal aging.


2021 ◽  
Author(s):  
Sarah A Johnson ◽  
Spencer L Seale ◽  
Rachel M Gittelman ◽  
Julie A Rytlewski ◽  
Harlan S Robins ◽  
...  

The human adaptive immune system must generate extraordinary diversity to be able to respond to all possible pathogens. The T-cell repertoire derives this high diversity through somatic recombination of the T-cell receptor (TCR) locus, a random process that results in repertoires that are largely private to each individual. However, certain factors such as low junctional diversity, thymic selection, and T-cell proliferation upon antigen exposure can affect TCR sharing among individuals. By immunosequencing the TCRβ variable region of 426 healthy individuals, we find that fewer than 1% of TCRβ clones are shared between individuals on average, consistent with largely private TCRβ repertoires. However, we detect a significant correlation between increased HLA allele sharing and increased number of shared TCRβ clones, with each additional shared HLA allele contributing to an increase in ~0.01% of the total TCRβ clones being shared, supporting a key role for HLA type in shaping the immune repertoire. Surprisingly, we find that shared antigen exposure to CMV leads to fewer shared TCRβ clones, even after controlling for HLA, indicative of a largely private response to major viral antigenic exposure. Consistent with this hypothesis, we find that increased age is correlated with decreased overall TCRβ clone sharing, indicating that the pattern of private TCRβ clonal expansion is a general feature of the T-cell response to other infectious antigens. All of these factors contribute to shaping the TCRβ repertoire, and understanding their interplay has important implications for the use of T cells for therapeutics and diagnostics.


PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0249484
Author(s):  
Sarah A. Johnson ◽  
Spencer L. Seale ◽  
Rachel M. Gittelman ◽  
Julie A. Rytlewski ◽  
Harlan S. Robins ◽  
...  

The human adaptive immune system must generate extraordinary diversity to be able to respond to all possible pathogens. The T-cell repertoire derives this high diversity through somatic recombination of the T-cell receptor (TCR) locus, a random process that results in repertoires that are largely private to each individual. However, factors such as thymic selection and T-cell proliferation upon antigen exposure can affect TCR sharing among individuals. By immunosequencing the TCRβ variable region of 426 healthy individuals, we find that, on average, fewer than 1% of TCRβ clones are shared between individuals, consistent with largely private TCRβ repertoires. However, we detect a significant correlation between increased HLA allele sharing and increased number of shared TCRβ clones, with each additional shared HLA allele contributing to an increase in ~0.01% of the total shared TCRβ clones, supporting a key role for HLA type in shaping the immune repertoire. Surprisingly, we find that shared antigen exposure to CMV leads to fewer shared TCRβ clones, even after controlling for HLA, indicative of a largely private response to major viral antigenic exposure. Consistent with this hypothesis, we find that increased age is correlated with decreased overall TCRβ clone sharing, indicating that the pattern of private TCRβ clonal expansion is a general feature of the T-cell response to other infectious antigens as well. However, increased age also correlates with increased sharing among the lowest frequency clones, consistent with decreased repertoire diversity in older individuals. Together, all of these factors contribute to shaping the TCRβ repertoire, and understanding their interplay has important implications for the use of T cells for therapeutics and diagnostics.


Author(s):  
Pieter Meysman ◽  
Anna Postovskaya ◽  
Nicolas De Neuter ◽  
Benson Ogunjimi ◽  
Kris Laukens

Much is still not understood about the human adaptive immune response to SARS-CoV-2, the causative agent of COVID-19. In this paper, we demonstrate the use of machine learning to classify SARS-CoV-2 epitope specific T-cell clonotypes in T-cell receptor (TCR) sequencing data. We apply these models to public TCR data and show how they can be used to study T-cell longitudinal profiles in COVID-19 patients to characterize how the adaptive immune system reacts to the SARS-CoV-2 virus. Our findings confirm prior knowledge that SARS-CoV-2 reactive T-cell diversity increases over the course of disease progression. However our results show a difference between those T cells that react to epitope unique to SARS-CoV-2, which show a more prominent increase, and those T cells that react to epitopes common to other coronaviruses, which begin at a higher baseline.


1996 ◽  
Vol 184 (5) ◽  
pp. 1919-1926 ◽  
Author(s):  
S Candéias ◽  
K Muegge ◽  
S K Durum

The site-specific V(D)J recombination reaction necessary to assemble the genes coding for immunoglobulin (Ig) and T cell receptor (TCR) variable regions is initiated by a precise double strand cut at the border of the recombination signals flanking the genes. Extensive processing of the coding ends before their ligation accounts for most of the Ig and TCR repertoire diversity. This processing includes both base additions to and loss from the coding ends. On the other hand, it has generally been thought that signal ends are not modified before they are fused, and that signal joints consist of a perfect head-to-head ligation of the recombination signals. In this study, we analyzed signal joints created during the rearrangement of different TCR-beta and TCR-delta genes in thymocytes. We show that a significant fraction (up to 24%) of these signal joints exhibits junctional diversity. This diversity results from N nucleotide additions for TCR-beta signal joints, and from N additions and exonucleolytic digestion for TCR-delta joints. Altogether, our findings suggest that: (a) signal ends can undergo some of the same modifications as coding ends, (b) inversional rearrangement generates more diversity than deletional events, and (c) fine differences exist in the recombinase/DNA complexes formed at each rearranging locus.


2021 ◽  
Vol 7 (20) ◽  
pp. eabf5835
Author(s):  
Wen Zhang ◽  
Peter G. Hawkins ◽  
Jing He ◽  
Namita T. Gupta ◽  
Jinrui Liu ◽  
...  

T cell receptor (TCR) antigen–specific recognition is essential for the adaptive immune system. However, building a TCR-antigen interaction map has been challenging due to the staggering diversity of TCRs and antigens. Accordingly, highly multiplexed dextramer-TCR binding assays have been recently developed, but the utility of the ensuing large datasets is limited by the lack of robust computational methods for normalization and interpretation. Here, we present a computational framework comprising a novel method, ICON (Integrative COntext-specific Normalization), for identifying reliable TCR-pMHC (peptide–major histocompatibility complex) interactions and a neural network–based classifier TCRAI that outperforms other state-of-the-art methods for TCR-antigen specificity prediction. We further demonstrated that by combining ICON and TCRAI, we are able to discover novel subgroups of TCRs that bind to a given pMHC via different mechanisms. Our framework facilitates the identification and understanding of TCR-antigen–specific interactions for basic immunological research and clinical immune monitoring.


iScience ◽  
2021 ◽  
Vol 24 (2) ◽  
pp. 102053
Author(s):  
Sanghoon Lee ◽  
Li Zhao ◽  
Latasha D. Little ◽  
Shannon N. Westin ◽  
Amir A. Jazarei ◽  
...  

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