The advance of next generation sequencing (NGS) techniques provides an unprecedented opportunity to probe the enormous diversity of the immune repertoire by deep sequencing T-cell receptors (TCRs) and B-cell receptors (BCRs). However, an efficient and accurate analytical tool is still on demand to process the huge amount of data. We have developed a high-resolution analytical pipeline, Immune Monitor ("IMonitor") to tackle this task. This method utilizes realignment to identify V(D)J genes and alleles after common local alignment. We compare IMonitor with other published tools by simulated and public rearranged sequences, and it demonstrates its superior performance in most aspects. Together with this, a methodology is developed to correct the PCR and sequencing errors and to minimize the PCR bias among various rearranged sequences with different V and J gene families. IMonitor provides general adaptation for sequences from all receptor chains of different species and outputs useful statistics and visualizations. In the final part of this article, we demonstrate its application on minimal residual disease detection in patients with B-cell acute lymphoblastic leukemia. In summary, this package would be of widespread usage for immune repertoire analysis.KEYWORDS next generation sequencing; bioinformatics; immune repertoire; TCR/BCR T HE diversity of T-cell receptors (TCRs), B-cell receptors (BCRs), and secreting form antibodies makes up the core of the complicated immune system and serves as pivotal defensive components to protect the body against invading virus, bacteria, and other pathogens. The TCR consists of a heterodimeric ab chain (95%, TRA, TRB) or gd chain (5%), while the BCR is assembled with two heavy chains (IGH) and two light chains (IGK or IGL). Structurally, each chain can be divided into the variable domain and the constant domain (Lefranc and Lefranc 2001a,b). The diversity of the TCR and BCR repertoire is enormous, owing to the process of V(D)J gene rearrangement, random deletion of germline nucleotides, and insertion of uncertain length of nontemplate nucleotides between V-D and D-J junctions (TRB, IGH) or V-J junctions (TRA, IGK, IGL). In humans, it has been estimated theoretically that the diversity of TCR-ab receptors exceeds 10 18 in the thymus, and the diversity of the B-cell repertoire is even larger, considering the somatic hypermutation (Janeway 2005;Benichou et al. 2012). The T-and B-cell repertoire could undergo dynamic changes under different phenotypic status. Recently, deep sequencing enabled by different platforms including Roche 454 and Illumina Hiseq (Freeman et al. 2009;Robins et al. 2009;Wang et al. 2010;Fischer 2011;Venturi et al. 2011) has been applied to unravel the dynamics of the TCR and BCR repertoire and extended to various translational applications such as vaccination, cancer, and autoimmune diseases.Several tools and software have been developed for TCR and BCR sequence analysis, including iHMMune-align (Gaeta et al. 2007), HighV-QEUST (Li et al. 2013), IgBLA...
T lymphocytes infiltrate the microenvironment of breast cancer tumors and play a pivotal role in tumor immune surveillance. Relationships between the T-cell receptors (TCR) borne by T cells within tumors, in the surrounding tissues, and in draining lymph nodes are largely unexplored in human breast cancer. Consequently, information about the relative extent of possible T-cell exchange between these tissues is also lacking. Here, we have analyzed the TCR repertoire of T cells using multiplex PCR and high-throughput sequencing of the TCRβ chain in the tissues of tumor, adjacent nontumor, and axillary lymph nodes of breast cancer patients. T-cell repertoire diversity in tumors was lower than in lymph nodes, but higher than in nontumor tissue, with a preferential use of variable and joining genes. These data are consistent with the hypothesis that most of the T cells in tumors derive from the lymph node, followed by their expansion in tumor tissue. Positive nodes appeared to enhance T-cell infiltration into tumors and T-cell clonal expansion in lymph nodes. Additionally, the similarity in TCR repertoire between tumor and nontumor tissue was significantly higher in luminal-like, rather than basal-like, breast cancer. Our study elucidated the high heterogeneity of the TCR repertoire and provides potential for future improvements in immune-related diagnosis, therapy, and prognosis for breast cancer patients. Cancer Immunol Res; 5(2); 148-56. ©2016 AACR.
High-throughput sequencing has recently been applied to profile the high diversity of antibodyome/B cell receptors (BCRs) and T cell receptors (TCRs) among immune cells. To date, Multiplex PCR (MPCR) and 5’RACE are predominately used to enrich rearranged BCRs and TCRs. Both approaches have advantages and disadvantages; however, a systematic evaluation and direct comparison of them would benefit researchers in the selection of the most suitable method. In this study, we used both pooled control plasmids and spiked-in cells to benchmark the MPCR bias. RNA from three healthy donors was subsequently processed with the two methods to perform a comparative evaluation of the TCR β chain sequences. Both approaches demonstrated high reproducibility (R2 = 0.9958 and 0.9878, respectively). No differences in gene usage were identified for most V/J genes (>60%), and an average of 52.03% of the CDR3 amino acid sequences overlapped. MPCR exhibited a certain degree of bias, in which the usage of several genes deviated from 5’RACE, and some V-J pairings were lost. In contrast, there was a smaller rate of effective data from 5’RACE (11.25% less compared with MPCR). Nevertheless, the methodological variability was smaller compared with the biological variability. Through direct comparison, these findings provide novel insights into the two experimental methods, which will prove to be valuable in immune repertoire research and its interpretation.
Acute B lymphoblastic leukemia (B-ALL) is one of the most common types of childhood cancer worldwide and chemotherapy is the main treatment approach. Despite good response rates to chemotherapy regiments, many patients eventually relapse and minimal residual disease (MRD) is the leading risk factor for relapse. The evolution of leukemic clones during disease development and treatment may have clinical significance. In this study, we performed immunoglobulin heavy chain (IGH) repertoire high throughput sequencing (HTS) on the diagnostic and post-treatment samples of 51 pediatric B-ALL patients. We identified leukemic IGH clones in 92.2% of the diagnostic samples and nearly half of the patients were polyclonal. About one-third of the leukemic clones have correct open reading frame in the complementarity determining region 3 (CDR3) of IGH, which demonstrates that the leukemic B cells were in the early developmental stage. We also demonstrated the higher sensitivity of HTS in MRD detection and investigated the clinical value of using peripheral blood in MRD detection and monitoring the clonal IGH evolution. In addition, we found leukemic clones were extensively undergoing continuous clonal IGH evolution by variable gene replacement. Dynamic frequency change and newly emerged evolved IGH clones were identified upon the pressure of chemotherapy. In summary, we confirmed the high sensitivity and universal applicability of HTS in MRD detection. We also reported the ubiquitous evolved IGH clones in B-ALL samples and their response to chemotherapy during treatment.
The B cells inhabited in mucosa play a vital role in mediating homeostasis with autoantigens and external Ags. Tumorinfiltrating lymphocytes are potential prognostic markers and therapeutic agents for cancer. However, the spatial heterogeneity of the B cell repertoire in intestinal mucosa and the tumor-infiltrating lymphocytes in colorectal cancer (CRC) remain poorly understood. In this study, we developed an unbiased method to amplify the IgH repertoire, as well as a bioinformatic pipeline to process these high-throughput sequencing data. With biopsies from seven intestinal mucosal segments, we uncovered their strong spatial homogeneity among the large intestine, where the clone overlap rate was up to 62.21%. The heterogeneity between terminal ileum and large intestine was also observed, including discrepant isotype distribution and low clone overlap rate. With tumor and adjacent normal mucosal tissues from CRC and colorectal advanced adenoma (AD) patients, we observed a similar IgH profile between tumor and adjacent normal mucosal tissues in AD, as well as a slight difference in CRC. Interestingly, we found distinct repertoire properties in the CRC tumor from AD and normal mucosa. Finally, we identified 1445 public clones for the normal mucosa, and 22 public clones for the CRC tumor with characteristic features. These data may be of potential use in clinical prognosis, diagnosis, and treatment of CRC.
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