Reduced expression of a human V beta 6.1 T-cell receptor allele

Variability in TRBV haplotype frequency and composition in Caucasian, African American, Western African and Chinese populations

The polymorphic T-cell receptor Vbeta (TRBV) genes encode much of the variable region of the T-cell receptor beta chain. Analysis of allele frequencies of three closely linked polymorphic TRBV genes, TRBV7-3, TRBV9 and TRBV6-4, was undertaken in several populations. The frequencies of these alleles are not significantly different in populations of Caucasians, African Americans and Western Africans. However, Chinese population is extremely homogenous at all three loci. The current study identifies the existence of haplotypic relationships between alleles of these genes in the Caucasian population. The ORF allele TRBV7-3*A3 is found exclusively on chromosomes bearing TRBV9*A2 and TRBV6-4*A2 in this cohort. In contrast, TRBV7-3*A1 and the null allele TRBV7-3*A2 are associated only with TRBV9*A1 and TRBV6-4*A1. This pattern of linkage disequilibrium (LD) is altered in the African American and Western African populations. In these cohorts, there is a marked reduction in LD between alleles of TRBV7-3 and TRBV9. This study is consistent with previous population genetic studies wherein African-derived samples have a greater level of genetic diversity compared to Caucasians. These data also demonstrate that patterns of LD are not consistent across the entire TRBV locus.

Genomic absence of the gene encoding T cell receptor Vbeta7.2 is linked to the presence of autoantibodies in Sjögren's syndrome

OBJECTIVE

It is not yet known whether the absence of certain T cell receptor V(beta) (TCRBV) genes (e.g., due to genomic deletion) has functional significance. We examined this question in relation to a known 21.6-kb insertion/deletion-related polymorphism (IDRP) in the human BV locus.

METHODS

New polymerase chain reaction (PCR) genotyping methods were used. Monoclonal antibodies to TCRBV gene products were used to confirm the absence of the relevant proteins. Patients with Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) were compared with normal controls with regard to TCR genotypes and serologic profiles.

RESULTS

There are 3 known haplotypes (I, D1, D2) and 6 possible genotypes related to the 21.6-kb IDRP. Novel PCR-based methods were used to define these genotypes. In subjects with deleted/deleted (D/D) genotypes, T cells could not express V(beta)7.2 TCRs, as assayed with a new antibody specific for V(beta)7.2. This was the sole significant difference between subjects without the insertion and those with either 1 or 2 copies. Surprisingly, we found that the D/D genotype was associated with primary SS, but only when pathogenic autoantibodies were present.

CONCLUSION

These results suggest that T cells expressing TCRs with V(beta)7.2 are protective against a pathogenic immune response in SS. Thus, genomic polymorphism of TCR genes (along with the correct HLA alleles) determines whether T cells can direct a pathogenic autoimmune response.

Three-dimensional structural location and molecular functional effects of missense SNPs in the T cell receptor V? domain

The mechanisms by which human single nucleotide polymorphisms (SNPs) influence susceptibility to disease are not yet well understood. In a previous study, we developed a structure-based model that may be used to identify which missense SNPs are neutral and which are deleterious to protein function and so potentially involved in disease (Wang and Moult, Hum Mutat 2001;263-270). The model has now been applied to a set of 54 missense cSNPs in the 46 functional T-cell receptor Vbeta-genes. Most of these missense cSNPs are found to be neutral, but 10 are identified as likely deleterious to protein function. Only one was previously associated with disease. We suggest that the others may be disease related but that redundancy in the T-cell response prevents any simple, monogenic effect. Therefore, these SNPs are the most likely contributors to complex, polygenic disease traits. It has been noted that there is a surprisingly high (74%) fraction of nonsynonymous SNPs in these genes. Contrary to expectation, the analysis shows that these are not associated with an unusually high fraction of deleterious SNPs, nor do they significantly contribute to a larger range of antigen recognition or a reduced superantigen-binding repertoire.

Sequence variation and linkage disequilibrium in the human T-cell receptor beta (TCRB) locus

The T-cell receptor (TCR) plays a central role in the immune system, and > 90% of human T cells present a receptor that consists of the alpha TCR subunit (TCRA) and the beta subunit (TCRB). Here we report an analysis of 63 variable genes (BV), spanning 553 kb of TCRB that yielded 279 single-nucleotide polymorphisms (SNPs). Samples were drawn from 10 individuals and represent four populations-African American, Chinese, Mexican, and Northern European. We found nine variants that produce nonfunctional BV segments, removing those genes from the TCRB genomic repertoire. There was significant heterogeneity among population samples in SNP frequency (including the BV-inactivating sites), indicating the need for multiple-population samples for adequate variant discovery. In addition, we observed considerable linkage disequilibrium (LD) (r(2) > 0.1) over distances of approximately 30 kb in TCRB, and, in general, the distribution of r(2) as a function of physical distance was in close agreement with neutral coalescent simulations. LD in TCRB showed considerable spatial variation across the locus, being concentrated in "blocks" of LD; however, coalescent simulations of the locus illustrated that the heterogeneity of LD we observed in TCRB did not differ markedly from that expected from neutral processes. Finally, examination of the extended genotypes for each subject demonstrated homozygous stretches of >100 kb in the locus of several individuals. These results provide the basis for optimization of locuswide SNP typing in TCRB for studies of genotype-phenotype association.

A novel polymorphism in the pseudogene TCRBV5S5 combines with TCRBV6S1 to define three haplotypes

In the current study, we report a G to A single nucleotide polymorphism at base pair 396 of the TCRBV5S5P gene. This polymorphism has a frequency of 0.20 in a cohort of Caucasian controls. In addition, we provide evidence for linkage disequilibrium between TCRBV5S5P and the TCRBV6S1 gene.

Chemokine Receptor CCR4 on CD4+ T Cells in Juvenile Rheumatoid Arthritis Synovial Fluid Defines a Subset of Cells with Increased IL-4:IFN-γ mRNA Ratios

To understand the mechanisms that promote recruitment and survival of T cells within the pediatric inflamed joint, we have studied the expression of CCR4 and CCR5 on synovial fluid T cells and matched peripheral blood samples from juvenile rheumatoid arthritis (JRA) patients using three-color flow cytometric analysis. Thymus- and activation-regulated chemokine and macrophage-derived chemokine, ligands for CCR4, were measured by ELISA in JRA synovial fluid, JRA plasma, adult rheumatoid arthritis synovial fluid, and normal plasma. IL-4 and IFN-gamma mRNA production was assessed in CD4+/CCR4+ and CD4+/CCR4(-) cell subsets. We found accumulations of both CCR4+ and CCR5+ T cells in JRA synovial fluids and a correlation for increased numbers of CCR4+ T cells in samples collected early in the disease process. Thymus- and activation-regulated chemokine was detected in JRA synovial fluid and plasma samples, but not in adult rheumatoid arthritis synovial fluid or control plasma. Macrophage-derived chemokine was present in all samples. CD4+/CCR4+ synovial lymphocytes produced more IL-4 and less IFN-gamma than CD4+/CCR4(-) cells. These findings suggest that CCR4+ T cells in the JRA joint may function early in disease in an anti-inflammatory capacity through the production of type 2 cytokines and may play a role in determining disease phenotype.

The nonfunctional allele TCRBV6S1B is strongly associated with Helicobacter pylori infection

To determine genetic susceptibility factors for Helicobacter pylori infection, polymorphic T-cell receptor gene elements were investigated in 203 H. pylori-infected individuals and 180 uninfected individuals (controls). H. pylori infection is highly associated with individuals homozygous for the nonfunctional TCRBV6S1B element (odds ratio = 5.9; chi(2) = 13; P = 0.00032; P value corrected for multiple comparisons [Bonferroni correction] = 0. 00063).

Human T-cell receptor BV6 gene polymorphism in relation to expression level and CD4/CD8 skewness

Using 50 samples of umbilical cord blood lymphocytes from Japanese donors, we analysed two human T-cell receptor beta variable (TCRBV) genes, BV6S4 and BV6S5, for their polymorphism, usage frequencies and CD4/CD8 skewness. They showed contrasting CD4/CD8 skewness, BV6S4 to CD8+ T cells and BV6S5 to CD4+ T cells. Genotyping of the BV6S4 alleles (A1, A2 and A3) revealed two of the six possible BV6S4 genotypes, A1/A2 and A2/A2. Among the two BV6S4 genotypes, no significant difference was detected in usage frequency or CD4/CD8 skewness. On the other hand, genotyping of the BV6S5 alleles (A1 and A2) revealed all three possible BV6S5 genotypes, A1/A1, A1/A2 and A2/A2, and the gene usage frequency was high, in the order A1/A1 > A1/A2 > A2/A2. These results indicate that the amino acid substitutions in BV6S5 (S36R and G70E) are in some way associated with the expression level of this gene. In the analysis of CD4/CD8 skewness, the three BV6S5 genotypes had similar skewness, indicating that A1 alleles are expressed more frequently than A2 alleles in both CD4+ and CD8+ T-cell populations. Although BV6S5 exhibits marked skewness to CD4+ T cells, our results indicate that the higher expression of A1 alleles is not associated with the increased ratio of CD4+ T cells.

Comparative sequence analysis of the human T cell receptor beta chain in juvenile rheumatoid arthritis and juvenile spondylarthropathies: evidence for antigenic selection of T cells in the synovium

OBJECTIVE

To identify features of the T cell receptors (TCRs) present on clonally expanded T cells in the joints of patients with similar types of childhood rheumatic disease. Vbeta8 and Vbeta20 TCRs were selected as prototypic for polyarticular juvenile rheumatoid arthritis (JRA) and pauciarticular/juvenile spondylarthropathy (SpA), respectively.

METHODS

The portion of the TCR beta chain involved in antigen recognition in the synovial tissue, synovial fluid, and peripheral blood from patients with JRA and juvenile SpA was cloned and sequenced. The frequency of expanded clonotypes, size of expansions, the Jbeta region, and sequence motifs were determined for >2,000 sequences.

RESULTS

The majority of Vbeta20 and Vbeta8 clonal expansions were found in the joint rather than the peripheral blood. While instances of both Vbeta8 and Vbeta20 clonal expansion were detected in all disease types, the features of these expanded clonotypes were specific for disease type and Vbeta family. For example, Vbeta20 clonal expansion was characterized by many small expanded clonotypes in samples from patients with pauciarticular JRA and juvenile SpA while single large Vbeta8-specific expansions were found only in patients with polyarticular disease. Motifs specific to individual patients were identified, and for Vbeta20 clonotypes, a motif was found in synovial tissue samples.

CONCLUSION

Identification of common TCR features in oligoclonal expansions within individual patients and between patients with the same type of JRA suggests the recognition of a common or limited group of antigens in these diseases.

The human immunoglobulin V(H) gene repertoire is genetically controlled and unaltered by chronic autoimmune stimulation

The factors controlling immunoglobulin (Ig) gene repertoire formation are poorly understood. Studies on monozygotic twins have helped discern the contributions of genetic versus environmental factors on expressed traits. In the present experiments, we applied a novel anchored PCR-ELISA system to compare the heavy chain V gene (V(H)) subgroup repertoires of mu and gamma expressing B lymphocytes from ten pairs of adult monozygotic twins, including eight pairs who are concordant or discordant for rheumatoid arthritis. The results disclosed that the relative expression of each Ig V(H) gene subgroup is not precisely proportional to its relative genomic size. The monozygotic twins had more similar IgM V(H) gene repertoires than did unrelated subjects. Moreover, monozygotic twins who are discordant for RA also use highly similar IgM V(H) gene-subgroup repertoires. Finally, the V(H) gene repertoire remained stable over time. Collectively, these data reveal that genetic factors predominantly control V(H) gene repertoire formation.

TCR gene polymorphisms and autoimmune disease

Autoimmunity may result from abnormal regulation within the immune system. As the T cell is the principal regulator of the immune system and its normal function depends on immune recognition or self/non-self discrimination, abnormalities of the idiotypic T-cell receptor (TCR) may be one cause of autoimmune disease. The TCR is a clonally distributed, cell-surface heterodimer which binds peptide antigen when complexed with HLA molecules. In order to recognize the variety of antigens it may possibly encounter, the TCR, by necessity, is a diverse structure. As with immunoglobulin, it is the variable domain of the TCR which interacts with antigen and exhibits the greatest amount of amino acid variability. The underlying genetic basis for this structural diversity is similar to that described for immunoglobulin, with TCR diversity relying on the somatic recombination, in a randomly imprecise manner, of smaller gene segments to form a functional gene. There are a large number of gene segments to choose from (particularly the TCRAV, TCRAJ and TCRBV gene segments) and some of these also exhibit allelic variation. Finally, polymorphisms in non-coding regions of TCR genes, leading to biased recombination or expression, are also beginning to be recognized. All these factors contribute to the polymorphic nature of the TCR, in terms of both structure and repertoire formation. It follows that inherited abnormalities in either coding or regulatory regions of TCR genes may predispose to aberrant T-cell function and autoimmune disease. This review will outline the genomic organization of the TCR genes, the genetic mechanisms responsible for the generation of diversity, and the results of investigations into the association between germline polymorphisms and autoimmune disease.

Human T-cell receptor variable gene segment families

Multiple DNA and protein sequence alignments have been constructed for the human T-cell receptor alpha/delta, beta, and gamma (TCRA/D, B, and G) variable (V) gene segments. The traditional classification into subfamilies was confirmed using a much larger pool of sequences. For each sequence, a name was derived which complies with the standard nomenclature. The traditional numbering of V gene segments in the order of their discovery was continued and changed when in conflict with names of other segments. By discriminating between alleles at the same locus versus genes from different loci, we were able to reduce the number of more than 150 different TCRBV sequences in the database to a repertoire of only 47 functional TCRBV gene segments. An extension of this analysis to the over 100 TCRAV sequences results in a predicted repertoire of 42 functional TCRAV gene segments. Our alignment revealed two residues that distinguish between the highly homologous V delta and V alpha, one at a site that in VH contacts the constant region, the other at the interface between immunoglobulin VH and VL. This site may be responsible for restricted pairing between certain V delta and V gamma chains. On the other hand, V beta and V gamma appear to be related by the fact that their CDR2 length is increased by four residues as compared with that of V alpha/delta peptides.

Immunopathogenesis of juvenile rheumatoid arthritis: role of T cells and MHC

Juvenile rheumatoid arthritis (JRA) is defined as chronic arthritis of unknown etiology appearing in patients less than 16 years of age. The disease is heterogeneous and is classified as pauciarticular, polyarticular, or systemic-onset disease. A few lines of evidence suggest that T cells are involved in the pathogenesis of the disease. T cells infiltrating the synovial membrane bear markers of activation and produce cytokines. The association of particular subtypes of JRA with certain HLA class II alleles provides strong evidence in favor of T cell involvement through an HLA-peptide-T cell receptor complex. Limited data from a few patients with JRA on T cell receptor transcripts from synovial membrane or synovial fluid cells point towards oligoclonality. This further supports the concept that T cells infiltrating the synovial membrane or extravasating into synovial fluid in patients with JRA reflect antigen-driven T cell proliferation.

PCR-based genotyping and haplotype analysis of human TCRBV gene segment polymorphisms

There are at least 63 tandemly arranged human T-cell receptor (Tcr) beta-chain variable region (BV) gene segments, which have presumably arisen by repeated gene duplication events. The 5'-most half of the TCRBV gene loci is particularly complex in organization due to the presence of multiple interspersed members of the largest BV subfamilies, BV5, BV6, and BV13. Polymorphism and linkage relationships among these genes has been poorly characterized in part due to the high similarity of these duplicands. Germline DNA polymorphisms were specifically examined in the exons and introns of these and other BV gene segments distributed across 240 kilobases (kb) in this 5'-most region. Polymerase chain reaction restriction enzyme-based assays were used to genotype ten point mutations in seven of the BV gene segments. Eight of these polymorphisms altered an amino acid of the BV gene segment. In addition, length polymorphisms due to simple sequence repeats were noted in the introns of six BV6 subfamily members. Approximately 250 unrelated haplotypes were constructed by segregation analyses of fifteen of these TCRBV polymorphisms. Linkage disequilibrium analyses indicated that haplotypic relationships are not detectable over a distance of more than 55 kb in this genomic region. These TCRBV polymorphisms, and the haplotypic analysis, provide important resources and guidance for future attempts to associate Tcr germline DNA differences in the human population with immune response differences, such as might occur in some autoimmune diseases.

Environmental and genetic factors shape the human T-cell receptor repertoire

Both environmental and genetic factors combine to shape the TCR repertoire as measured by V gene usage. These factors may result in dramatic shifts in normal subjects, which cannot be discounted when studies are performed in patients with disease. Future studies need to explore further examples of genetic and environmental factors that shape the TCR repertoire to understand the full extent of variation in a normal population and the mechanisms involved. Some of these mechanisms may also apply to TCRG, TCRD, and immunoglobulin loci. Certainly variations in the efficiency of V(D)J rearrangement could affect any rearranging multigene locus. Eventually such studies will lead to better designed clinical studies of the repertoire in disease, through the selection of control populations matched for environmental exposure and genetic background. In this respect, family studies will be most useful.

The basis of autoimmunity: Part II. Genetic predisposition

In Part II of his review of the basis of autoimmunity, Argyrios N. Theofilopoulos summarizes current knowledge on the genetic factors that contribute to autoimmune disease predisposition. The findings indicate that multiple genes contribute to the induction of pathogenic autoimmunity, and that no single genetic abnormality is sufficient in itself to induce disease. The definition of these genetically complex diseases is about to be revolutionized by the development of genome scanning approaches, such as dense chromosomal maps based on polymorphic microsatellite DNA and other informative markers. These will allow the loci and genes that predispose to these diseases to be identified broadly.

A genetic association between juvenile rheumatoid arthritis and a novel interleukin-1 alpha polymorphism

OBJECTIVE

The genetic factors that predispose to the development of juvenile rheumatoid arthritis (JRA) and its complications are not completely understood. The cytokine interleukin-1 (IL-1) has been implicated in the pathogenesis of JRA and other inflammatory diseases. This study was performed to test whether polymorphisms of the IL-1 alpha gene might be associated with JRA.

METHODS

We sequenced the 5' regulatory region (containing the promoter) of the human IL-1 alpha gene in 18 normal subjects. This revealed a C (IL-1A1) to T (IL-1A2) transition polymorphism at position -889. We studied the frequencies of both alleles in patients with JRA (n = 269) and controls (n = 99).

RESULTS

An increased gene carriage of IL-1A2 was found in patients with early-onset, pauciarticular JRA (EOPA-JRA; n = 103) compared with controls (0.66 versus 0.49; P = 0.01, odds ratio [OR] = 2.1). Within this subset of JRA, the association with IL-1A2 was particularly strong in the patients in whom chronic iridocyclitis developed (n = 28) compared with those without chronic iridocyclitis (0.89 versus 0.57; P = 0.002, OR = 6.2). Within the group of EOPA-JRA patients, IL-1A2 was also associated with elevation of the erythrocyte sedimentation rate (P < 0.0025).

CONCLUSION

This is the first report of a cytokine gene association with JRA, and we conclude that IL-1 alpha itself, or a gene for which the IL-1 alpha polymorphism is a marker, may contribute to the pathogenesis of EOPA-JRA and the ocular complications found in this group.

Immunoprinting: various genes are associated with increased risk to develop rheumatoid arthritis in different groups of adult patients

To identify genes that contribute to the manifestation of rheumatoid arthritis we performed association studies via microsatellite analyses of immunorelevant loci (HLA-DRB, 5 T cell receptor loci, TNFa IL1, IL2, IL5R and CD40L). A total of 183 patients and 275 healthy controls were typed in terms of HLA and grouped according to the known predisposing HLA-DRB1 genes (DRB1*04; relative risk approx. 5; DRB1*01, relative risk approx. 2; a third group carried neither allele). Microsatellite polymorphisms characterizing the TCRBV6S3, CD3D, IL1A, IL2, and IL5R genes did not show significant associations with rheumatoid arthritis, whereas TCRBV6S1, TCRBV6S7, TNFa, and CD40L genes may influence relative protection or risk in certain groups of patients. Analysis of a microsatellite marker adjacent to the transcription element alpha (TEA) in the T cell receptor alpha delta complex indicates that in the cohort carrying neither the DRB1*04 nor the DRB1*01 allele the relative risk to acquire rheumatoid arthritis is increased (> 13) or decreased (< 0.07), depending on the inherited microsatellite allele adjacent to the TEA locus. Sequence analysis of the closely linked TEA region from patients and controls revealed a novel dimorphism. Only the newly identified TEA allele leads to binding of a nuclear protein that may be involved in the regulated expression of the TCRDA genes. Subsequent typing of rheumatoid arthritis patients and controls revealed, however, that the association of the microsatellite marker is largely independent of the TEA allele, confirming incomplete linkage in the 2 kb region of the TCRDA locus. These results are discussed in the context of hot spots of recombination in this genomic region and other linked candidate sequences that predispose to develop rheumatoid arthritis.

Genetic control of the human V beta 13.2 T cell repertoire: importance of allelic variation outside the coding regions of the TCRBV13S2 gene

In humans, the T cell repertoire is influenced by HLA, T cell receptor null alleles and antigen. Here, we describe a novel mechanism, independent of superantigen or T cell receptor structure which influences the T cell repertoire in a V beta-dependent manner. We have identified a biallelic locus, the TCRBV13S2 T cell receptor gene, where allelic differences predominate in the non-coding regions including transitions, transversions and frameshift deletions. The expressed protein is non-polymorphic at this locus. The TCRBV13S2 genotype profoundly influences the circulating levels of V beta 13.2 CD4 T cells but does not affect T cell receptor expression or function.

Genetic analysis of low V beta 3 expression in humans

While studying the T cell receptor (TCR) repertoire of normal individuals, we found that more than 20% of adults have low levels of circulating V beta 3.1+ T cells in both CD4 and CD8 populations. A similar frequency was found in fetal cord blood samples, suggesting that in most cases, the V beta 3.1low phenotype is inherited. In support of this conclusion, children expressing low levels were only found in families where one of the parents expressed this phenotype. In two large families, genetic studies showed that low expression was a recessive trait and dependent on inheritance of particular TCR VB gene complexes. Family members with the low phenotype, however, expressed VB3.1 genes with normal sequences and expressed normal levels of receptor per cell. Results from these families suggest that up to 50% of normal individuals may carry a VB3.1 allele that is defective in its ability to rearrange effectively. In another large family, low expression in one individual was shown not to be determined by genes within the TCR VB gene or major histocompatibility complexes, suggesting a different mechanism for low V beta 3.1+ T cells. Overall, our results describe novel mechanisms that result in low levels of V beta 3.1+ T cells in a relatively large subset of the normal human population.

Level of human TCRBV3S1 (V beta 3) expression correlates with allelic polymorphism in the spacer region of the recombination signal sequence

One of the causes of variations in the expressed human T cell receptor (TCR) BV (V beta) repertoire is genetic variation in the germline DNA. Herein evidence is provided that allelic polymorphism may affect recombination frequency for a specific V gene. Two alleles of the TCR BV3 differ only at a single nucleotide position (C/T) within the 23-bp spacer region of the recombination signal sequence. These alleles are associated with variable percentages of BV3 cells in the peripheral blood, as shown in families and in unrelated normal donors. Individuals homozygous for allele 2 have a mean of 8.1% BV3 cells, heterozygous individuals have a mean of 4.7% BV3 cells, and homozygotes for allele 1 have a mean of 1.2% BV3 cells in CD3+ CD4+ peripheral blood T cells. Since the correlation is tight in unrelated individuals and other genetic differences were not found in the vicinity of BV3, we suggest that the spacer region sequence itself modifies recombination efficiency. This allelic system provides an example of a novel mechanism by which cis-acting genetic elements may affect recombination in a natural in vivo system.

HLA and T cell receptor beta-chain DNA polymorphisms identify a distinct subset of patients with pauciarticular-onset juvenile rheumatoid arthritis

OBJECTIVE

To evaluate and extend upon a reported association of a T cell receptor (TCR) V beta coding region polymorphism with pauciarticular-onset juvenile rheumatoid arthritis (JRA).

METHODS

TCR V beta 6.1 genotypes and haplotypes in JRA and control groups were determined by DNA amplification.

RESULTS

Haplotypes of the V beta 6.1 gene which encode a nonfunctional form of V beta 6.1 were significantly associated with pauciarticular JRA in patients possessing the HLA-DQA1*0101 allele (P = 0.0073).

CONCLUSION

A TCR V beta gene segment in the vicinity of V beta 6.1, possibly V beta 6.1, is apparently involved in the pathogenesis of pauciarticular-onset JRA in DQA1*0101-positive individuals.

The extent of the human germline T-cell receptor V beta gene segment repertoire

An assessment of the size of the human TCRBV gene segment repertoire based on the identification of TCRBV gene segments in genomic DNA was undertaken. PCR amplification from cloned and uncloned genomic DNA sources, nucleotide sequencing, Southern blot hybridization, and cosmid cloning were used to identify TCRBV gene segments in multiple unrelated individuals. The key advantages to this approach were: 1) TCRBV gene segments which are expressed only at very low levels in cDNA libraries were still detectable, and 2) it was possible to discriminate between alleles at the same locus vs products of different loci. A total of 63 unique TCRBV gene segments were identified and sequenced. Six of these TCRBV gene segments had not been previously described. Thirty-four cosmid clones containing 51 of the 63 identified TCRBV gene segments were isolated and screened for the presence of additional novel TCRBV subfamily members. These results, obtained by a variety of complementary approaches, indicate that the human TCRBV germline repertoire encodes at least 63 TCRBV gene segments of which 52 are functional. The availability of the majority of these TCRBV gene segments on cosmid clones should facilitate further investigation of germline TCRBV gene segment polymorphism and putative disease associations.

Dominant T-cell-receptor beta chain variable region V beta 14+ clones in juvenile rheumatoid arthritis

The characteristic histopathology and major histocompatibility complex associations in juvenile rheumatoid arthritis suggest an oligoclonal antigen-specific T-cell population may be critical to pathogenesis. To test this, we analyzed the T-cell repertoire of a polyarticular HLA-DR4+ juvenile rheumatoid arthritis patient with an aggressive form of disease that required arthrocentesis of the knee joints and early replacement of both hip joints. A comparison of T-cell-receptor beta chain variable region (V beta) gene expression in peripheral blood and synovial fluid performed by semiquantitation of cDNA samples amplified by the PCR revealed overexpression of the T-cell-receptor V beta 14 gene family. To determine the nature of V beta 14 overexpression, we sequenced randomly cloned amplification products derived from two synovial fluid, two synovial tissue, and three peripheral blood samples by using a V beta 14/beta chain constant region primer pair. Sequence data showed that the T-cell response in the synovia was oligoclonal. Of four clones found, one was present in all joints examined and persisted over time. This clone accounted for 67% and 74% of all V beta 14+ clones sequenced in two synovial fluid samples and 75% and 40% in two synovial tissue samples. This clone was also found at a lesser frequency in peripheral blood samples. Further studies provided evidence for the presence of oligoclonally expanded populations of T cells utilizing the V beta 14 T-cell receptor in 6 of 27 patients examined. In contrast to the remaining patients studied, 3 with a late onset polyarticular course who exhibited especially marked clonality were characterized by features typical of adult rheumatoid arthritis (IgM rheumatoid factor-positive and HLA-DR4+). These data suggest a role for V beta 14+ T cells in a group of juvenile rheumatoid arthritis patients.