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The B cell receptor immunoglobulin (Ig) gene repertoires of marginal zone (MZ) lymphoproliferations were analyzed in order to obtain insight into their ontogenetic relationships. Our cohort included cases with MZ lymphomas (n = 488), i.e. splenic (SMZL), nodal (NMZL) and extranodal (ENMZL), as well as provisional entities (n = 76), according to the WHO classification. The most striking Ig gene repertoire skewing was observed in SMZL. However, restrictions were also identified in all other MZ lymphomas studied, particularly ENMZL, with significantly different Ig gene distributions depending on the primary site of involvement. Cross-entity comparisons of the MZ Ig sequence dataset with a large dataset of Ig sequences (MZ-related or not; n = 65 837) revealed four major clusters of cases sharing homologous ('public') heavy variable complementarity-determining region 3. These clusters included rearrangements from SMZL, ENMZL (gastric, salivary gland, ocular adnexa), chronic lymphocytic leukemia, but also rheumatoid factors and non-malignant splenic MZ cells. In conclusion, different MZ lymphomas display biased immunogenetic signatures indicating distinct antigen exposure histories. The existence of rare public stereotypes raises the intriguing possibility that common, pathogen-triggered, immune-mediated mechanisms may result in diverse B lymphoproliferations due to targeting versatile progenitor B cells and/or operating in particular microenvironments. Copyright (c) 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Background Antigen receptors are characterized by an extreme diversity of specificities, which poses major computational and analytical challenges, particularly in the era of high-throughput immunoprofiling by next generation sequencing (NGS). The T cell Receptor/Immunoglobulin Profiler (TRIP) tool offers the opportunity for an in-depth analysis based on the processing of the output files of the IMGT/HighV-Quest tool, a standard in NGS immunoprofiling, through a number of interoperable modules. These provide detailed information about antigen receptor gene rearrangements, including variable (V), diversity (D) and joining (J) gene usage, CDR3 amino acid and nucleotide composition and clonality of both T cell receptors (TR) and B cell receptor immunoglobulins (BcR IG), and characteristics of the somatic hypermutation within the BcR IG genes. TRIP is a web application implemented in R shiny. Results Two sets of experiments have been performed in order to evaluate the efficiency and performance of the TRIP tool. The first used a number of synthetic datasets, ranging from 250k to 1M sequences, and established the linear response time of the tool (about 6 h for 1M sequences processed through the entire BcR IG data pipeline). The reproducibility of the tool was tested comparing the results produced by the main TRIP workflow with the results from a previous pipeline used on the Galaxy platform. As expected, no significant differences were noted between the two tools; although the preselection process seems to be stricter within the TRIP pipeline, about 0.1% more rearrangements were filtered out, with no impact on the final results. Conclusions TRIP is a software framework that provides analytical services on antigen receptor gene sequence data. It is accurate and contains functions for data wrangling, cleaning, analysis and visualization, enabling the user to build a pipeline tailored to their needs. TRIP is publicly available at https://bio.tools/TRIP_-_T-cell_Receptor_Immunoglobulin_Profiler.

Chronic lymphocytic leukemia (CLL) displays extreme clinical heterogeneity likely reflecting the underlying biological heterogeneity. For this reason, intense research efforts have addressed progno...

Viral infections, mainly by cytomegalovirus (CMV), Epstein Barr virus (EBV) and polyomavirus type I (BKV), are major causes of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). As effective immune responses against human viruses rely on an armamentarium of T-cell receptor (TR) repertoire capable of recognizing a broad range of antigenic peptides of those pathogens, reconstitution of antiviral immunity, either by spontaneous generation of endogenous virus-specific T cells (VSTs) or by adoptive immunotherapy with VSTs, plays a critical role to fight infections. We here evaluated the diversity and clonality of TR repertoire of functional tri-virus-specific T cell products generated from immunocompetent donors (n=10) and compared their TR gene repertoire to that of peripheral blood mononuclear cells (PBMCs) from patients who had undergone allo-HSCT (n=5). To generate tri-VSTs, PBMCs derived from 15-20ml of peripheral blood of normal donors, were exposed to EBV, CMV and BKV overlapping peptides and cultured in the presence of interleukin 4 (IL-4) and IL-7 for 10 days in G-rex bioreactors. Specificity of donor-derived VSTs and patient-derived PBMCs was measured by IFN-γElispot. TR diversity was investigated by next-generation sequencing on a MiSeq Sequencer, after amplification of TR beta chain gene rearrangements by RT-PCR with the BIOMED-2 protocol. Raw NGS reads were filtered based on their length and quality and the filtered-in sequences were submitted to IMGT/HighVQUEST. Metadata analysis and clonotype computation were performed using a validated in-house bioinformatics platform. As clonotype we defined sequences carrying the same TRBV gene and identical CDR3 amino acid sequence. Tri-VSTs provided 947,298 productive TRBV-TRBD-TRBJ rearrangements and a polyclonal and highly diverse TR gene repertoire, consisting of a total of 169,502 unique clonotypes (average: 16,950/sample, range 4,057-45,602), 64,971 (38.3%) of which were expanded (corresponding to more than one sequence). In terms of clonality, the mean relative frequency of the major clonotype in all tri-VSTs was 12.6% (range 3.3-29.2%). Interestingly, among tri-VST cell lines, 637 clonotypes were shared (present in >2/10 samples), 80 were highly shared (present in >3/10 samples) while 7 were present in 6-8 different VST lines and largely expanded, accounting for up to 29.2% of all sequences. Importantly, there were 65 of 96 major VST clonotypes shared, thus suggesting that they were potentially associated with recognition of the targeted viruses. Given that 4/10 VSTs cell lines were not specific for CMV, while being EBV-and BKV-specific, dominant TRs in those 4 cell lines can potentially be associated with EBV- or BKV-activity. By searching a public database of TR clonotypes with known reactivity against EBV and/or CMV (ShugayM, Nucleic Acids Research, 2018), we found 8 shared EBV-specific and 4 shared CMV-specific clonotypes among our VSTs and the 499 public clonotypes. When we compared the produced VSTs with PBMCs from 3 allo-grafted patients with circulating CMV-, BKV- and EBV-specific T cells and previous viral reactivation, we detected 163 shared clonotypes. Likewise, we observed 21 and 23 shared clonotypes in similar frequencies, between VSTs and PBMCs from 2 patients with CMV- or BKV-specific T cell immunity. These data identify clones that potentially expand in vivo and protect patients from viral infections. Overall, our findings reveal high levels of TR clonality in cell lines enriched for T cells reactive against EBV and/or CMV and/or BKV and provide insights into the TR repertoire of ex vivo- or endogenously-generated VSTs. Our approach may help to identify optimal TRs for immunotherapy as well as TRs which can be used as a tool for risk stratification of viral infections. Disclosures Agathangelidis: Gilead: Research Funding. Gemenetzi:Gilead: Research Funding. Stamatopoulos:Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding. Hadzidimitriou:Gilead: Research Funding; Abbvie: Research Funding; Janssen: Honoraria, Research Funding.

Non-neoplastic lymphadenopathy (NNL) associated with the human immunodeficiency virus (HIV) infection may develop concurrently with the onset of HIV viremia (acute retroviral syndrome) that can persist beyond the acute phase. Histopathological findings at this early phase mainly pertain to hyperplastic changes with large lymphoid follicles; with time, the number of lymphoid follicles diminishes, while plasma cells increase; at the extreme is a pattern characterized by sclerosis of the germinal centers in the residual follicles. HIV-specific CD8+ T cell responses have been reported and certain viral protein epitopes have been identified e.g. the p24 protein, a component of the HIV particle capsid. Overall, these findings reflect an ongoing immune response that is still incompletely characterized at the molecular level, particularly as it concerns the composition of the T cell receptor (TR) gene repertoire. In order to obtain a comprehensive view into the role of antigen selection in shaping T cell responses in HIV-associated NNL [HIV(+) NNL], we studied in-depth the TR repertoire in: (i) lymph node biopsy samples from 12 patients with HIV(+) NNL, (ii) lymph node samples from 5 non-HIV patients with reactive lymphadenopathy [HIV(-) RL]; and, (iii) peripheral blood samples from 4 healthy, HIV-seronegative individuals without lymphadenopathy [healthy controls, HIV(-) HC]. Genomic DNA was isolated from either paraffin-embedded lymph nodes (for patients with lymphadenopathy) or blood mononuclear cells (for healthy individuals). TRBV-TRBD-TRBJ gene rearrangements were amplified according to the BIOMED2 protocol. PCR products were subjected to next generation sequencing (NGS) on the MiSeq Illumina Platform. NGS data analysis, interpretation and visualization was performed by a validated, in-house bioinformatics pipeline. Overall, we obtained: (i) 1,440,305 (mean: 120,025) productive rearrangement sequences in the HIV(+) NNL group; (ii) 702,533 (mean: 140,506) productive sequences in the HIV(-) RL group; and, (iii) 539,981 (mean: 134,995) productive sequences in HIV(-) HC cases. Rearrangements with identical TRBV gene usage and CDR3 sequence were defined as clonotypes. In total, we identified 15,553 unique clonotypes in patients with HIV(+) NNL (mean: 1,296, range: 337-6,212), 53,874 in HIV(-) RL (mean: 10,774, range: 3,336-16,304) and 220,069 clonotypes in HIV(-) HC cases (mean; 55,017, range: 35,430-68,916), indicating significant repertoire restriction in the former group. Indeed, this group was characterized by an increased level of oligoclonality compared to the other two groups: the mean values of the sum of relative frequencies for the 10 most frequent clonotypes were 80%, 19.6% and 16.5%, respectively. Seven of 12 HIV(+) NNL cases carried the same dominant clonotype (TRBV29-1, SVDPSGTGGEGYT) that was also found in the remaining 5 patients of this group, albeit at lower frequencies; in contrast, it was completely absent in the HIV(-) RL and HIV(-) HC groups. Regarding the TRBV gene repertoire, the TRBV29-1 gene was overrepresented (p Disclosures Gemenetzi: Gilead: Research Funding. Agathangelidis:Gilead: Research Funding. Stamatopoulos:Janssen: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Hadzidimitriou:Gilead: Research Funding; Janssen: Honoraria, Research Funding; Abbvie: Research Funding.

Subset #2 is the largest subset carrying stereotyped B cell receptor immunoglobulin (BcR IG) in chronic lymphocytic leukemia (CLL). This particular BcR IG is composed of heavy (HC) and light (LC) chains encoded by the IGHV3-21 and the lambda IGLV3-21 gene, respectively. The clonotypic IGHV3-21 genes display a variable load of somatic hypermutation (SHM), being mostly classified as mutated (M-CLL) but also including unmutated (U-CLL) cases. Subset #2 cases, independently of the SHM status, have a particularly dismal clinical outcome similar to that of patients with TP53 aberrations, although lacking such aberrations. Subset #2 BcR IG display a series of distinctive features, including conservation at certain VH and VL CDR3 positions and recurrent SHMs; as well as a capacity for self-association leading to cell autonomous signaling that is critically dependent on a substitution of Arginine (R) for Glycine (G) introduced by SHM at the lambda VL-CL linker region. These features implicate antigen selection in CLL subset #2 ontogeny. However, the available molecular evidence derives from low throughput immunogenetic analysis, precluding comprehensive assessment of antigenic impact on (sub)clonal composition. Here, we sought to overcome this limitation by performing next-generation sequencing (NGS) of HC and LC gene rearrangements of 20 subset #2 patients. RT-PCR products amplified by the IGHV3-21/IGHJ6 and IGLV3-21/IGLC primer pairs, respectively, were subjected to NGS on the MiSeq Illumina Platform. NGS data was analyzed by a validated bioinformatics pipeline. Rearrangements with identical CDR3 amino acid (aa) sequences were defined as clonotypes, whereas clonotypes with different aa substitutions within the V-domain were defined as subclones. Starting with HCs, we obtained 3,340,508 (mean: 291,751, range: 101,231-186,055) productive reads. On average, each analyzed sample carried 92 distinct clonotypes (range: 71-152), with the dominant clonotype having a mean frequency of 96% (range: 67-99%): in all cases the dominant clonotype was identical to that determined by Sanger sequencing. The dominant clonotype displayed considerable intraclonal heterogeneity with a mean of 5,082 subclones/sample (range: 2,946-11,041). Turning to LCs, we obtained 5,094,045 (mean: 231,547, range: 38,036-507,949) productive reads. LCs carried a higher number of distinct clonotypes/sample compared to their partner HCs (mean 222, range: 156-306). The dominant clonotype had a mean frequency of 96% (range: 74-98%); similar to HCs, it was identical to that determined by Sanger sequencing. Intraclonal heterogeneity was observed in the LCs as well, with a mean of 7,382 subclones/sample (range: 1,946-11,866), hence more pronounced vs their partner HCs. Viewing the entire subset #2 VH or VL CDR3 dataset (i.e. the CDR3 aa sequences from all clonotypes of all cases) as a single entity branching through diversification enabled the identification of 2 distinct VH CDR3 sequences present at varying frequencies in 16 and 13 cases, respectively; and, 3 distinct VL CDR3 sequences present at varying frequencies in all 20 cases: these results allude to important constraints on the composition of the antigen binding site. Focusing on SHM, the following notable observations could be made. (i) The G-to-R substitution at the VL-CL linker was a clonal event in all cases with R being degenerately encoded by different nucleotide sequences; altogether, these findings underscore the seminal role of this recurrent SHM, likely due to mediating self-association. (ii) A recurrent 3-nucleotide deletion was detected in the VH CDR2 of all cases, strongly supporting functional pressure. This change, previously identified by Sanger sequencing as a recurrent SHM in subset #2 (albeit at a frequency of only 25%), was clonal in 4 cases and subclonal in the remainder, where it was present in an average of 105 subclones/sample (range: 1-369). (iii) Certain positions in both the VH and VL domain bore the same aa substitution, mostly at subclonal level: the prime example concerned the G for Serine (S) substitution within the VL CDR3, detected in all samples at a mean frequency of 44.2% (range: 6.3-87%). In conclusion, we provide compelling immunogenetic evidence for functional pressure in the ontogeny of CLL subset #2. On this evidence, subset #2 emerges as perhaps the most striking example of antigen-driven leukemogenesis reported thus far. Disclosures Gemenetzi: Gilead: Research Funding. Agathangelidis:Gilead: Research Funding. Stamatopoulos:Abbvie: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Hadzidimitriou:Abbvie: Research Funding; Gilead: Research Funding; Janssen: Honoraria, Research Funding.

Chronic lymphocytic leukemia (CLL) patients assigned to stereotyped subset #4 (mutated IGHV4-34/IGKV2-30 BCR Ig) display a particularly indolent disease course. Immunogenetic studies of the clonotypic BCR Ig of CLL subset #4 suggested a resemblance with B cells rendered anergic through chronic autoantigenic stimulation. In this article, we provide experimental evidence that subset #4 CLL cells show low IgG levels, constitutive ERK1/2 activation, and fail to either release intracellular Ca2+ or activate MAPK signaling after BCR cross-linking, thus displaying a signature of B cell anergy at both biochemical and functional levels. Interestingly, TLR1/2 triggering restored BCR functionality, likely breaching the anergic state, and this was accompanied by induction of the miR-17∼92 cluster, whose members target critical BCR-associated molecules, including MAPKs. In conclusion, we demonstrate BCR anergy in CLL subset #4 and implicate TLR signaling and the miR-17∼92 cluster in the regulation of the anergic state. This detailed signaling profiling of subset #4 has implications for advanced understanding of the complex regulation of intracellular signaling pathways in CLL, currently a major therapeutic target of the disease.