Genomic V exons from whole genome shotgun data in reptiles

Reptiles and mammals diverged over 300 million years ago, creating two parallel evolutionary lineages amongst terrestrial vertebrates. In reptiles, two main evolutionary lines emerged: one gave rise to Squamata, while the other gave rise to Testudines, Crocodylia, and Aves. In this study, we determined the genomic variable (V) exons from whole genome shotgun sequencing (WGS) data in reptiles corresponding to the three main immunoglobulin (IG) loci and the four main T cell receptor (TR) loci. We show that Squamata lack the TRG and TRD genes, and snakes lack the IGKV genes. In representative species of Testudines and Crocodylia, the seven major IG and TR loci are maintained. As in mammals, genes of the IG loci can be grouped into well-defined IMGT clans through a multi-species phylogenetic analysis. We show that the reptilian IGHV and IGLV genes are distributed amongst the established mammalian clans, while their IGKV genes are found within a single clan, nearly exclusive from the mammalian sequences. The reptilian and mammalian TRAV genes cluster into six common evolutionary clades (since IMGT clans have not been defined for TR). In contrast, the reptilian TRBV genes cluster into three clades, which have few mammalian members. In this locus, the V exon sequences from mammals appear to have undergone different evolutionary diversification processes that occurred outside these shared reptilian clans. These sequences can be obtained in a freely available public repository (http://vgenerepertoire.org).     

Immunoglobulin heavy- and light-chain repertoire in splenic marginal zone lymphoma

The considerable heterogeneity in morphology, immunophenotype, genotype, and clinical behavior of splenic marginal zone lymphoma (SMZL) hinders firm conclusions on the origin and differentiation stage of the neoplastic cells. Immunoglobulin (IG) gene usage and somatic mutation patterns were studied in a series of 43 SMZL cases. Clonal IGHV-D-J rearrangements were amplified in 42/43 cases (4 cases carried double rearrangements). Among IGHV-D-J rearrangements, IGHV3 and IGHV4 subgroup genes were used with the highest frequency. Nineteen IGHV genes were unmutated (> 98% homology to the closest germline IGHV gene), whereas 27/46 were mutated. Clonal IGKV-J and IGLV-J gene rearrangements were amplified in 36/43 cases, including 31 IGKV-J (8/31 in lambda light-chain expressing cases) and 12 IGLV-J rearrangements; 9/31 IGKV and 6/12 IGLV sequences were mutated. IGKV-J and IGLV-J rearrangements used 14 IGKV and 9 IGLV different germline genes. Significant evidence for positive selection by classical T-dependent antigen was found in only 5/27 IGHV and 6/15 IGKV+IGLV mutated genes. These results provide evidence for the diverse B-cell subpopulations residing in the SMZ, which could represent physiologic equivalents of distinct SMZL subtypes. Furthermore, they indicate that in SMZL, as in other B cell malignancies, a complementarity imprint of antigen selection might be witnessed either by IGHV, IGKV, or IGLV rearranged sequences.     

IMGT,the international ImMunoGeneTics database

The international ImMunoGeneTics database (IMGT) (http://imgt.cines.fr), is a high quality integrated information system specializing in Immunoglobulins (IG), T cell Receptors (TR) and Major Histocompatibility Complex (MHC) of human and other vertebrates, created in 1989, by the Laboratoire d'ImmunoGénétique Moléculaire (LIGM), at the Université Montpellier II, CNRS, Montpellier, France. IMGT provides a common access to standardized data which include nucleotide and protein sequences, oligonucleotide primers, gene maps, genetic polymorphisms, specificities, 2D and 3D structures. IMGT includes three sequence databases (IMGT/LIGM-DB, IMGT/MHC-DB, IMGT/PRIMER-DB), one genome database (IMGT/GENE-DB) with different interfaces (IMGT/GeneSearch, IMGT/GeneView, IMGT/LocusView), one 3D structure database (IMGT/3Dstructure-DB), Web resources comprising 8000 HTML pages ('IMGT Marie-Paule page') and interactive tools for sequence analysis (IMGT/V-QUEST, IMGT/JunctionAnalysis, IMGT/Allele-Align, IMGT/PhyloGene). IMGT data are expertly annotated according to the rules of the IMGT Scientific chart, based on IMGT-ONTOLOGY. IMGT tools are particularly useful for the analysis of the IG and TR repertoires in physiological normal and pathological situations. IMGT has important applications in medical research (autoimmune diseases, AIDS, leukemias, lymphomas, myelomas), biotechnology related to antibody engineering (phage displays, combinatorial libraries) and thera-peutic approaches (graft, immunotherapy). IMGT is freely available at http://imgt.cines.fr.     

IMGT/HighV-QUEST: the IMGT® web portal for immunoglobulin (IG) or antibody and T cell receptor (TR) analysis from NGS high throughput and deep sequencing

Background: The number of antigen receptors, immunoglobulins (IG) or antibodies and T cell receptors (TR) of the adaptive immune response in vertebrates with jaws is almost unlimited (2.1012 per individual in humans). IMGT®, the international ImMunoGeneTics information system®, has developed online tools that provide a detailed and accurate sequence analysis of the V domains (IMGT/V-QUEST) and CDR3 (IMGT/JunctionAnalysis), based on IMGT-ONTOLOGY. However online analyses are limited to 50 sequences per batch. The challenge was to provide identical high quality analysis for the huge number of sequences obtained by Next Generation Sequencing (NGS) high throughput and deep sequencing.Results: IMGT® has developed IMGT/HighV-QUEST that analyses up to 150,000 IG or TR V domain sequences per batch and performs statistical analysis on the results of up to 450,000 sequences. IMGT/HighV-QUEST provides users with: (i) a friendly web interface for submission and results retrieval, (ii) high quality detailed results of IMGT/V-QUEST and IMGT/JunctionAnalysis, based on the IMGT-ONTOLOGY concepts and IMGT Scientific chart rules, (iii) a standardized frame for NGS statistical analysis, based on ‘Results category’ (‘1 copy’, ‘More than 1’, ‘single allele’, ‘several alleles (or genes)’, (iv) detailed standardized statistical analysis tables and histograms (e.g., V, D and J usage, CDR3-IMGT lengths).Conclusions: IMGT/HighV-QUEST has been freely available for use for academics on the IMGT® Home page (http://www.imgt.org) since October 2010. More than 123 million sequences were submitted during its first year. IMGT/HighV-QUEST is a key component for establishing reliable repertoires of IG and TR V domains. These repertoires will contribute to the individual immunoprofiles in diverse immune situations and on different B and T cell populations. They will also contribute to characterize potential therapeutic antibodies from combinatorial libraries.     

The human anti-thyroid peroxidase autoantibody repertoire in Graves' and Hashimoto's autoimmune thyroid diseases

Human anti-thyroid peroxidase (TPO) autoantibodies (aAb) are generated during autoimmune thyroid diseases (AITD). Within recent years, increasing knowledge of the TPO-specific aAb repertoire, gained mainly by the use of combinatorial library methodology, has led to the cloning and sequencing of around 180 human anti-TPO aAb. Analysis of the immunoglobulin (Ig) variable (V) genes encoding the TPO aAb in the ImMunoGeneTics database (IMGT) (http://imgt.cines.fr) reveals major features of the TPO-directed aAb repertoire during AITD. Heavy chain VH domains of TPO-specific aAb from Graves' disease patients preferentially use D proximal IGHV1 genes, whereas those from Hashimoto's thyroiditis are characterized more frequently by IGHV3 genes, mainly located in the middle of the IGH locus. A large proportion of the anti-TPO heavy chain VH domains is obtained following a VDJ recombination process that uses inverted D genes. J distal IGKV1 and IGLV1 genes are predominantly used in TPO aAb. In contrast to the numerous somatic hypermutations in the TPO-specific heavy chains, there is only limited amino acid replacement in most of the TPO-specific light chains, particularly in those encoded by J proximal IGLV or IGKV genes, suggesting that a defect in receptor editing can occur during aAb generation in AITD. Among the predominant IGHV1 or IGKV1 TPO aAb, conserved somatic mutations are the hallmark of the TPO aAb repertoire. The aim of this review is to provide new insights into aAb generation against TPO, a major autoantigen involved in AITD.     

IMGT-ONTOLOGY for immunogenetics and immunoinformatics

IMGT, the international ImMunoGeneTics information system(R) (http://imgt.cines.fr), is a high quality integrated knowledge resource specializing in immunoglobulins (IG), T cell receptors (TR), major histocompatibility complex (MHC) and related proteins of the immune system (RPI) of human and other vertebrates, created in 1989, by the Laboratoire d'ImmunoGenetique Moleculaire LIGM. IMGT provides a common access to standardized data which include nucleotide and protein sequences, oligonucleotide primers, gene maps, genetic polymorphisms, specificities, 2D and 3D structures. IMGT consists of several sequence databases (IMGT/LIGM-DB, IMGT/MHC-DB, IMGT/PRIMER-DB), one genome database (IMGT/GENE-DB) and one three-dimensional structure database (IMGT/3Dstructure-DB), interactive tools for sequence analysis (IMGT/V-QUEST, IMGT/JunctionAnalysis, IMGT/PhyloGene, IMGT/Allele-Align), for genome analysis (IMGT/GeneSearch, IMGT/GeneView, IMGT/LocusView) and for 3D structure analysis (IMGT/StructuralQuery), and Web resources ("IMGT Marie-Paule page") comprising 8000 HTML pages. IMGT other accesses include SRS, FTP, search by BLAST, etc. By its high quality and its easy data distribution, IMGT has important implications in medical research (repertoire in autoimmune diseases, AIDS, leukemias, lymphomas, myelomas), veterinary research, genome diversity and genome evolution studies of the adaptive immune responses, biotechnology related to antibody engineering (scFv, phage displays, combinatorial libraries) and therapeutical approaches (grafts, immunotherapy). IMGT is freely available at http://imgt.cines.fr.     

Mutation pattern of paired immunoglobulin heavy and light variable domains in chronic lymphocytic leukemia B cells

B-cell chronic lymphocytic leukemia (CLL) patients display leukemic clones bearing either germline or somatically mutated immunoglobulin heavy variable (IGHV ) genes. Most information on CLL immunoglobulins (Igs), such as the definition of stereotyped B-cell receptors (BCRs), was derived from germline unmutated Igs. In particular, detailed studies on the distribution and nature of mutations in paired heavy- and light-chain domains of CLL clones bearing mutated Igs are lacking. To address the somatic hyper-mutation dynamics of CLL Igs, we analyzed the mutation pattern of paired IGHV-diversity-joining (IGHV-D-J ) and immunoglobulin kappa/lambda variable-joining (IGK/LV-J ) rearrangements of 193 leukemic clones that displayed ≥ 2% mutations in at least one of the two immunoglobulin variable (IGV ) genes (IGHV and/or IGK/LV ). The relationship between the mutation frequency in IGHV and IGK/LV complementarity determining regions (CDRs) and framework regions (FRs) was evaluated by correlation analysis. Replacement (R) mutation frequency within IGK/LV chain CDRs correlated significantly with mutation frequency of paired IGHV CDRs in λ but not κ isotype CLL clones. CDRs of IGKV-J rearrangements displayed a lower percentage of R mutations than IGHVs. The frequency/pattern of mutations in kappa CLL Igs differed also from that in κ-expressing normal B cells described in the literature. Instead, the mutation frequency within the FRs of IGHV and either IGKV or IGLV was correlated. Notably, the amount of diversity introduced by replaced amino acids was comparable between IGHVs and IGKVs. The data indicate a different mutation pattern between κ and λ isotype CLL clones and suggest an antigenic selection that, in κ samples, operates against CDR variation.     

IMGT standardization for statistical analyses of T cell receptor junctions: the TRAV-TRAJ example

The diversity of immunoglobulin (IG) and T cell receptor (TR) chains depends on several mechanisms: combinatorial diversity, which is a consequence of the number of V, D and J genes and the N-REGION diversity, which creates an extensive and clonal somatic diversity at the V-J and V-D-J junctions. For the IG, the diversity is further increased by somatic hypermutations. The number of different junctions per chain and per individual is estimated to be 10(12). We have chosen the human TRAV-TRAJ junctions as an example in order to characterize the required criteria for a standardized analysis of the IG and TR V-J and V-D-J junctions, based on the IMGT-ONTOLOGY concepts, and to serve as a first IMGT junction reference set (IMGT, http://imgt.cines.fr). We performed a thorough statistical analysis of 212 human rearranged TRAV-TRAJ sequences, which were aligned and analysed by the integrated IMGT/V-QUEST software, which includes IMGT/JunctionAnalysis, then manually expert-verified. Furthermore, we compared these 212 sequences with 37 other human TRAV-TRAJ junction sequences for which some particularities (potential sequence polymorphisms, sequencing errors, etc.) did not allow IMGT/JunctionAnalysis to provide the correct biological results, according to expert verification. Using statistical learning, we constructed an automatic warning system to predict if new, automatically analysed TRAV-TRAJ sequences should be manually re-checked. We estimated the robustness of this automatic warning system.     

IMGT®, the International ImMunoGeneTics Information System® for Immunoinformatics

IMGT, the International ImMunoGeneTics information system ( http://imgt.cines.fr ), was created in 1989 by the Laboratoire d'ImmunoGénétique Moléculaire (LIGM) (Université Montpellier 2 and CNRS) at Montpellier, France, in order to standardize and manage the complexity of immunogenetics data. IMGT is recognized as the international reference in immunogenetics and immunoinformatics. IMGT is a high quality integrated knowledge resource, specialized in (i) the immunoglobulins (IG), T cell receptors (TR), major histocompatibility complex (MHC) of human and other vertebrates; (ii) proteins that belong to the immunoglobulin superfamily (IgSF) and to the MHC superfamily (MhcSF); and (iii) related proteins of the immune systems (RPI) of any species. IMGT provides a common access to standardized data from genome, proteome, genetics, and three-dimensional (3D) structures for the IG, TR, MHC, IgSF, MhcSF, and RPI. IMGT interactive on-line tools are provided for genome, sequence, and 3D structure analysis. IMGT Web resources comprise 10,000 HTML pages of synthesis and knowledge (IMGT Scientific chart, IMGT Repertoire, IMGT Education, etc.) and external links (IMGT Bloc-notes and IMGT other accesses).     

Evolution of the porcine (<Emphasis Type="Italic">Sus scrofa domestica</Emphasis>) immunoglobulin kappa locus through germline gene conversion

Immunoglobulin (IG) gene rearrangement and expression are central to disease resistance and health maintenance in animals. The IG kappa (IGK) locus in swine (Sus scrofa domestica) contributes to approximately half of all antibody molecules, in contrast to many other Cetartiodactyla, whose members provide the majority of human dietary protein and in which kappa locus utilization is limited. The porcine IGK variable locus is 27.9 kb upstream of five IG kappa J genes (IGKJ) which are separated from a single constant gene (IGKC) by 2.8 kb. Fourteen variable genes (IGKV) were identified, of which nine are functional and two are open reading frame (ORF). Of the three pseudogenes, IGKV3-1 contains a frameshift and multiple stop codons, IGKV7-2 contains multiple stop codons, and IGKV2-5 is missing exon 2. The nine functional IGKV genes are phylogenetically related to either the human IGKV1 or IGKV2 subgroups. IGKV2 subgroup genes were found to be dominantly expressed. Polymorphisms were identified on overlapping BACs derived from the same individual such that 11 genes contain amino acid differences. The most striking allelic differences are present in IGKV2 genes, which contain as many as 16 amino acid changes between alleles, the majority of which are in complementarity determining region (CDR) 1. In addition, many IGKV2 CDR1 are shared between genes but not between alleles, suggesting extensive diversification of this locus through gene conversion.     

IMGT-Choreography for immunogenetics and immunoinformatics

IMGT, the international ImMunoGeneTics information system (http://imgt.cines.fr), was created in 1989 at Montpellier, France. IMGT is a high quality integrated knowledge resource specialized in immunoglobulins (IG), T cell receptors (TR), major histocompatibility complex (MHC) of human and other vertebrates, and related proteins of the immune system (RPI) which belong to the immunoglobulin superfamily (IgSF) and MHC superfamily (MhcSF). IMGT provides a common access to standardized data from genome, proteome, genetics and three-dimensional structures. The accuracy and the consistency of IMGT data are based on IMGT-ONTOLOGY, a semantic specification of terms to be used in immunogenetics and immunoinformatics. IMGT-ONTOLOGY has been formalized using XML Schema (IMGT-ML) for interoperability with other information systems. We are developing Web services to automatically query IMGT databases and tools. This is the first step towards IMGT-Choreography which will trigger and coordinate dynamic interactions between IMGT Web services to process complex significant biological and clinical requests. IMGT-Choreography will further increase the IMGT leadership in immunogenetics and immunoinformatics for medical research (repertoire analysis of the IG antibody sites and of the TR recognition sites in autoimmune and infectious diseases, AIDS, leukemias, lymphomas, myelomas), veterinary research (IG and TR repertoires in farm and wild life species), genome diversity and genome evolution studies of the adaptive immune responses, biotechnology related to antibody engineering (single chain Fragment variable (scFv), phage displays, combinatorial libraries, chimeric, humanized and human antibodies), diagnostics (detection and follow up of residual diseases) and therapeutical approaches (grafts, immunotherapy, vaccinology). IMGT is freely available at http://imgt.cines.fr.     

Analyses of recombinant stereotypic IGHV3-21-encoded antibodies expressed in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) cells that use IgH encoded by IGHV3-21 and that have a particular stereotypic third CDR (HCDR3), DANGMDV (motif-1), almost invariably express Ig L chains (IgL) encoded by IGLV3-21, whereas CLL that use IGHV3-21-encoded IgH with another stereotypic HCDR3, DPSFYSSSWTLFDY (motif-2), invariably express κ-IgL encoded by IGKV3-20. This nonstochastic pairing could reflect steric factors that preclude these IgH from pairing with other IgL or selection for an Ig with a particular Ag-binding activity. We generated rIg with IGHV3-21-encoded IgH with HCDR3 motif-1 or -2 and IgL encoded by IGKV3-20 or IGLV3-21. Each IgH paired equally well with matched or mismatched κ- or λ-IgL to form functional Ig, which we screened for binding to an array of different Ags. Ig with IGLV3-21-encoded λ-IgL could bind with an affinity of ～ 2 × 10(-6) M to protein L, a cell-wall protein of Peptostreptococcus magnus, independent of the IgH, indicating that protein L is a superantigen for IGLV3-21-encoded λ-IgL. We also detected Ig binding to cofilin, a highly conserved actin-binding protein. However, cofilin binding was independent of native pairing of IgH and IgL and was not specific for Ig with IgH encoded by IGHV3-21. We conclude that steric factors or the binding activity for protein L or cofilin cannot account for the nonstochastic pairing of IgH and IgL observed for the stereotypic Ig made by CLL cells that express IGHV3-21.     

SAIVGeM: spreadsheet analysis of immunoglobulin VH gene mutations

The analysis of mutations in immunoglobulin heavy chain variable (IGHV) region genes is a tedious process when performed by hand on multiple sequences. This report describes a set of linked Microsoft Excel files that perform several common analyses on large numbers of IGHV sequences. The spreadsheet analysis of immunoglobulin VH gene mutations (SAIVGeM) package determines the distribution of mutations among each nucleotide, the nature of the mutation at both the nucleotide and amino acid level, the frequency of mutation in the A/G G C/T A/T (RGYW) hotspot motifs of both strand polarity, and the distribution of replacement and silent mutations among the complementarity determining regions (CDRs) and the framework regions (FRs) of the immunoglobulin gene as defined by either the Kabat or IMGT conventions. These parameters are summarized and graphically presented where appropriate. In addition, the SAIVGeM package analyzes those mutations that occur in third positions of redundant codons. Because any nucleotide change in these positions is inherently silent, these positions can be used to study the mutational spectra without biases from the selection of protein structure.     

Genomic<Emphasis Type="Italic"> Eco</Emphasis>RI polymorphism and cosmid sequencing reveal an insertion/deletion and a new<Emphasis Type="Italic"> IGLV5</Emphasis> allele in the human immunoglobulin lambda variable locus (22q11.2/IGLV)

The human immunoglobulin lambda locus ( IGL) is mapped at Chromosome 22q11.2, spanning about 1 Mb of DNA, and directs the synthesis of lambda-type immunoglobulin light chains. The positions of about 73-74 germline V-lambda genes, depending on the haplotypes, are known, with 29-33 of them being functional IGLV genes. These genes were divided into 11 subgroups ( IGLV1 to IGLV11) distributed into three gene clusters ( VA, VB, and VC). We constructed a high-resolution restriction map of a 37-kb cosmid clone (cosmid 8.3) harboring genes of the IGLV1, IGLV7, and IGLV5 families and the non-coding sequences IGLV(I)-42 and IGLV(VII)-41-1, located at cluster VB of the IGL locus. These IGLV genes were associated with unique EcoRI fragments detectable in Southern blots of genomic DNA. Population RFLP has revealed new IGLV alleles and haplotypes. We used the restriction map of cosmid 8.3 and the IMGT database as a reference for RFLP studies. EcoRI Southern blot hybridizations with subgroup-specific probes of the functional and open reading frame sequences present in cosmid 8.3 revealed different frequencies of IGLV gene fragments, as well as deletions of IGLV1-50 and IGLV5-39 genes and RFLP involving IGLV5-45 and IGLV5-48 genes. All members of the IGLV7 subgroup were monomorphic. Sequencing of the genes present in cosmid 8.3 revealed a new allelic variant of the IGLV5 subgroup. These data contribute to a better understanding of the contribution of the germline IGLV genes to the human genetic background and polymorphism.     

IMGT, the international ImMunoGeneTics database

IMGT, the international ImMunoGeneTics database (http://imgt.cines. fr:8104 ), is a high-quality integrated database specialising in Immunoglobulins (Ig), T cell Receptors (TcR) and Major Histocompatibility Complex (MHC) molecules of all vertebrate species, created in 1989 by Marie-Paule Lefranc, Université Montpellier II, CNRS, Montpellier, France (lefranc@ligm.igh.cnrs.fr ). At present, IMGT includes two databases: IMGT/LIGM-DB, a comprehensive database of Ig and TcR from human and other vertebrates, with translation for fully annotated sequences, and IMGT/HLA-DB, a database of the human MHC referred to as HLA (Human Leucocyte Antigens). The IMGT server provides a common access to expertized genomic, proteomic, structural and polymorphic data of Ig and TcR molecules of all vertebrates. By its high quality and its easy data distribution, IMGT has important implications in medical research (repertoire in autoimmune diseases, AIDS, leukemias, lymphomas), therapeutic approaches (antibody engineering), genome diversity and genome evolution studies. IMGT is freely available at http://imgt.cines.fr:8104. The IMGT Index is provided at the IMGT Marie-Paule page (http://imgt.cines.fr:8104/textes/IMGTindex.html).     

The reported germline repertoire of human immunoglobulin kappa chain genes is relatively complete and accurate

We describe a bioinformatic analysis of germline and rearranged immunoglobulin kappa chain (IGK) gene sequences, performed in order to assess the completeness and reliability of the reported IGK repertoire. In contrast to the reported heavy-chain gene repertoire, which includes many dubious sequences, only five IGK variable gene (IGKV) alleles appear to have been reported in error. There was, however, insufficient evidence to justify removing these IGKV genes from the germline repertoire. Bioinformatic analysis of apparent mismatches between reported germline genes and 1,863 expressed IGK sequences suggested the existence of two unreported IGKV polymorphisms. Genomic screening of 12 individuals led to the confirmation of both of these polymorphisms, IGKV1-16*02 and IGKV2-30*02. We also show that in contrast to the heavy chain, the IGK repertoire is dominated by sequences that use just a handful of kappa variable (IGKV) and junction (IGKJ) gene pairs. There is also little modification of IGKV and IGKJ genes by the processes of exonuclease removal and N nucleotide addition. The expressed IGK repertoire therefore lacks diversity and the junction region is particularly constrained. Remarkably, the analysis of a dataset of 435 relatively unmutated rearranged kappa genes showed that ten amino acid sequences account for almost 10% of the rearrangements, with identical sequences being derived from as many as seven independent sources. Such dominant sequences are likely to have important roles in the operation of the humoral immune response.     

IMGT, the International ImMunoGeneTics database.

IMGT, the international ImMunoGeneTics database, is an integrated database specialising in Immunoglobulins (Ig), T cell Receptors (TcR) and Major Histocompatibility Complex (MHC) of all vertebrate species, created by Marie-Paule Lefranc, CNRS, Montpellier II University, Montpellier, France (lefranc@ligm.crbm.cnrs-mop.fr). IMGT includes three databases: LIGM-DB (for Ig and TcR), MHC/HLA-DB and PRIMER-DB (the last two in development). IMGT comprises expertly annotated sequences and alignment tables. LIGM-DB contains more than 23 000 Immunoglobulin and T cell Receptor sequences from 78 species. MHC/HLA-DB contains Class I and Class II Human Leucocyte Antigen alignment tables. An IMGT tool, DNAPLOT, developed for Ig, TcR and MHC sequence alignments, is also available. IMGT works in close collaboration with the EMBL database. IMGT goals are to establish a common data access to all immunogenetics data, including nucleotide and protein sequences, oligonucleotide primers, gene maps and other genetic data of Ig, TcR and MHC molecules, and to provide a graphical user friendly data access. IMGT has important implications in medical research (repertoire in autoimmune diseases, AIDS, leukemias, lymphomas), therapeutical approaches (antibody engineering), genome diversity and genome evolution studies. IMGT is freely available at http://imgt.cnusc.fr:8104