A method for production of antibodies to human T-cell receptor beta-chain variable regions

Innate TCRβ-chain engagement drives human T cells toward distinct memory-like effector phenotypes with immunotherapeutic potentials

Clonotypic αβ T cell responses to cargoes presented by major histocompatibility complex (MHC), MR1, or CD1 proteins underpin adaptive immunity. Those responses are mostly mediated by complementarity-determining region 3 motifs created by quasi-random T cell receptor (TCR) gene rearrangements, with diversity being highest for TCRγδ. Nonetheless, TCRγδ also displays nonclonotypic innate responsiveness following engagement of germline-encoded Vγ-specific residues by butyrophilin (BTN) or BTN-like (BTNL) proteins that uniquely mediate γδ T cell subset selection. We now report that nonclonotypic TCR engagement likewise induces distinct phenotypes in TCRαβ+ cells. Specifically, antibodies to germline-encoded human TCRVβ motifs consistently activated naïve or memory T cells toward core states distinct from those induced by anti-CD3 or superantigens and from others commonly reported. Those states combined selective proliferation and effector function with activation-induced inhibitory receptors and memory differentiation. Thus, nonclonotypic TCRVβ targeting broadens our perspectives on human T cell response modes and might offer ways to induce clinically beneficial phenotypes in defined T cell subsets.

Engineering improved T cell receptors using an alanine-scan guided T cell display selection system

T cell receptors (TCRs) on T cells recognize peptide-major histocompatibility complex (pMHC) molecules on the surface of antigen presenting cells and this interaction determines the T cell immune response. Due to negative selection, naturally occurring TCRs bind self (tumor) peptides with low affinity and have a much higher affinity for foreign antigens. This complicates isolation of naturally occurring, high affinity TCRs that mediate more effective tumor rejection for therapeutic purposes. An attractive approach to resolve this issue is to engineer high affinity TCRs in vitro using phage, yeast or mammalian TCR display systems. A caveat of these systems is that they rely on a large library by random mutagenesis due to the lack of knowledge regarding the specific interactions between the TCR and pMHC. We have focused on the mammalian retroviral display system because it uniquely allows for direct comparison of TCR-pMHC-binding properties with T-cell activation outcomes. Through an alanine-scanning approach, we are able to quickly map the key amino acid residues directly involved in TCR-pMHC interactions thereby significantly reducing the library size. Using this method, we demonstrate that for a self-antigen-specific human TCR (R6C12) the key residues for pMHC binding are located in the CDR3β region. This information was used as a basis for designing an efficacious TCR CDR3α library that allowed for selection of TCRs with higher avidity than the wild-type as evaluated through binding and activation experiments. This is a direct approach to target specific TCR residues in TCR library design to efficiently engineer high avidity TCRs that may potentially be used to enhance adoptive immunotherapy treatments.

Epstein-Barr virus latent membrane protein LMP-2A is sufficient for transactivation of the human endogenous retrovirus HERV-K18 superantigen

Superantigens are microbial proteins that strongly stimulate T cells. We described previously that the Epstein-Barr virus (EBV) transactivates a superantigen encoded by the human endogenous retrovirus, HERV-K18. We now report that the transactivation is dependent upon the EBV latent cycle proteins. Moreover, LMP-2A is sufficient for induction of HERV-K18 superantigen activity.

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.

Epstein-Barr virus transactivates the human endogenous retrovirus HERV-K18 that encodes a superantigen

Superantigens (SAgs) are proteins produced by pathogenic microbes to elicit potent, antigen-independent T cell responses that are believed to enhance the microbes' pathogenicity. Here we show that the human lymphotropic herpesvirus Epstein-Barr virus (EBV) transcriptionally activates the env gene of an endogenous retrovirus, HERV-K18, that possesses SAg activity. SAg activity was demonstrated by MHC class II dependent preferential activation of TCRVB13 T cells in response to murine B cells transfected with the HERV-K18 env gene. This is a unique demonstration of a pathogen inducing a host-encoded Sag and accounts for the previously described EBV associated Sag activity. The T cell activation elicited by the Sag could play a central role in EBV infection and associated diseases.

Functional subsets within clonally expanded CD8(+) memory T cells in elderly humans

With advancing age, healthy humans frequently demonstrate large clonal expansions of CD8(+) T cells in the peripheral blood, which persist for long periods of time and appear to be maintained as a population of memory cells. We studied nine large T cell clones in five elderly individuals. We noted that in most cases the expanded clones were dominated by cells that did not express CD28, a pivotal molecule in T cell activation, and these clones proliferated poorly in culture. However, nearly all of the clonal expansions had CD28(+) fractions and some of these cells appeared to lose CD28 gene expression with stimulation in culture. CD28(+) cells demonstrated greater proliferation in both bulk and limiting dilution cultures compared to CD28(-) cells bearing the same TCR, whereas CD28(-) cells showed increased perforin expression. Together, these data suggest that loss of CD28 expression marks functional differentiation to cytotoxic memory cells within these clonal expansions and likely within CD8(+) memory populations in general.

Regional variation in the lamina propria T cell receptor V beta repertoire in normal human colon

Lamina propria (LP) T cell populations in the normal human colon contain oligoclonal expansions, but their distribution has not been well studied. We analyzed T cell receptor (TCR) beta-chain (V beta) variable region expression in CD4(+) and CD8(+) peripheral blood T cells and LP T cells from separated colonic segments in 13 subjects. CD4(+) and CD8(+) V beta subset expansions were found in the LP of most individuals, and remarkable differences in CD4(+) and CD8(+) TCR repertoires were apparent between colon and blood as well as between colon segments within each individual. The presence of such T cell expansions in colon therefore cannot be used to infer immunopathology. In addition, CD8(+) V beta expansions seen in peripheral blood T cells, which have been previously shown to be clonal in origin, were also often expanded in LP T cells of the same subject. These results suggest that LP CD8(+) T cell stimulation may contribute to CD8(+) peripheral blood T cell expansions.

A 15-year follow-up of AJCC stage III malignant melanoma patients treated postsurgically with Newcastle disease virus (NDV) oncolysate and determination of alterations in the CD8 T cell repertoire

BACKGROUND

The development of effective adjuvant therapies for the treatment of high-risk melanoma patients is critical for the prevention of metastatic disease and improvement of patient survival. Active specific immunotherapy has been tested as an adjuvant treatment in numerous clinical trials with overall limited, but occasionally promising, success rates. Newcastle disease virus (NDV) oncolysate has been utilized as an adjunctive immunotherapeutic agent in the postsurgical management of these patients. A phase II study initiated in 1975 using adjuvant vaccine therapy composed of allogeneic and autologous human melanoma cells infected with live NDV (NDV oncolysate) in patients with AJCC stage III melanoma following therapeutic lymph node dissection has shown >60% survival rate at 10 years with no adverse effects. Continued long-term analysis of trials with promising early results as well as assessment of immunologic responses generated in these patients may result in improved therapeutic decisions for clinical trials in the future.

MATERIALS AND METHODS

We analyzed the 15-year survival of patients treated postsurgically with NDV oncolysate in the phase II study described above. In an attempt to understand the immunological effects of this treatment, we have also carried out a comprehensive analysis of the peripheral blood T cell repertoire in these patients.

RESULTS

The overall 15-year survival of this group of patients is 55%. Previous studies have suggested that improved outcome in patients undergoing immunotherapy is correlated with increased numbers of CD8(+)CD57(+) cells. In surviving patients, we observed a striking oligoclonality in the CD8(+) T cell population in peripheral blood, which reflects clonal expansions in the CD8(+)CD57(+) subset.

CONCLUSIONS

The data suggest that adjuvant vaccination with NDV oncolysates is associated with prolonged survival of patients with lymph node-positive malignant melanoma and that CD8(+) T cells may be an important component of therapeutic efficacy.

A novel immunosuppressant, FTY720, increases the efficiency of a superantigen-induced peripheral T-cell deletion whilst inhibiting negative selection in the thymus

A novel immunosuppressant, FTY720, was generated by chemical modification of ISP-I, an immunosuppressive compound purified from culture filtrates of Isaria sinclairii. FTY720 directly induces apoptotic cell death in lymphocytes, which is believed to be the mechanism by which this drug exerts its immunosuppressive effect. We examined the effect of FTY720 treatment on antigen-induced apoptotic cell death in peripheral T cells and thymocytes. A superantigen, staphylococcus enterotoxin B (SEB), induces T-cell antigen receptor (TCR) Vbeta-specific apoptotic cell death in mature T cells in vivo. In this well-documented experimental system, FTY720 administration significantly enhanced the efficiency of superantigen-induced T-cell deletion. We also determined that apoptotic cell death with DNA fragmentation induced in T-hybridoma cells after stimulation in vitro with anti-TCR antibodies was enhanced in the presence of non-cytolytic doses of FTY720. In sharp contrast, negative selection of T cells in the thymus, another example of antigen-induced apoptosis, was found to be inhibited by FTY720 treatment. A rescue effect was observed on clonal deletion in the H-Y-specific TCRalpha beta transgenic male thymus. In a chicken egg albumin (OVA)-specific TCRalphabeta transgenic system, OVA-induced apoptotic cell death of CD4+CD8+ thymocytes was also inhibited by FTY720 injection. Thus, FTY720 increased the susceptibility of mature T cells to TCR-mediated apoptosis but decreased that of immature thymocytes. The results in this report suggest that the potent immunosuppressive effect of FTY720 is, in part, a result of the augmentation of effects on antigen-induced apoptosis in mature T cells, and that two distinct apoptotic cell death pathways are operating in mature and immature T cells.

Expansions of T-cell subsets expressing particular T-cell receptor variable regions in chronic beryllium disease

Chronic beryllium disease (CBD) is a granulomatous disorder characterized by the presence of noncaseating granulomas and mononuclear cell inflammation, occurring in 1 to 5% of people exposed to beryllium in the workplace. In the lungs of affected patients, CD4(+) T cells accumulate. Using anti-T-cell receptor (TCR) monoclonal antibodies, we investigated the TCR beta and alpha variable (Vbeta and Valpha, respectively) repertoire in the bronchoalveolar lavage (BAL) and blood of both CBD patients and healthy controls. There was marked heterogeneity within the BAL CD4(+) T-cell repertoire in both patients and controls. However, 11 of the 28 CBD patients demonstrated 16 different T-cell subset expansions within the BAL as compared with only one expansion in ten healthy controls. Five of the 16 expansions in CBD patients expressed Vbeta3. Altered TCR expression within the BAL T-cell repertoire appeared to persist over time in patients who underwent repeat evaluation. After in vitro stimulation of BAL T cells with beryllium sulfate and interleukin-2, we noted further alteration of the BAL TCR repertoire in some individuals. These results provide additional insight into the involvement of CD4(+) T cells in this disease and form the basis for studies to examine the nature of the stimulating antigen.

An Epstein-Barr virus-associated superantigen

More than 90% of adults are latently infected with Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, a self-limiting lymphoproliferative disease characterized by extensive T cell activation. Reactivation of this herpesvirus during immunosuppression is often associated with oncogenesis. These considerations led us to analyze the early events that occur after exposure of the immune system to EBV. Strong major histocompatibility complex (MHC) class II-dependent but not MHC-restricted, T cell proliferation was observed in vitro in response to autologous, lytically infected EBV-transformed B cells. By measuring the appearance of the early activation marker CD69 on individual T cell V beta subsets, we could demonstrate selective activation of human V beta 13- T cells. This was confirmed with murine T cell hybridomas expressing various human BV genes. While EBV- Burkitt's lymphoma cells were nonstimulatory, they induced V beta-restricted T cell activation after EBV infection. EBV specific activation was also demonstrated in cord blood cells, excluding a recall-antigen response. Thus, all of the characteristics of a superantigen-stimulated response are seen, indicating that induction of the EBV lytic cycle is associated with the expression of a superantigen in B cells. A model is presented proposing a role for the superantigen in infection, latency, and oncogenesis.

Large clonal expansions of CD8+ T cells in acute infectious mononucleosis

Primary infection with Epstein-Barr virus often results in the clinical syndrome of acute infectious mononucleosis (glandular fever). This illness is characterized by a striking lymphocytosis, the nature of which has been controversial. We show that large monoclonal or oligoclonal populations of CD8+ T cells account for a significant proportion of the lymphocytosis and provide molecular evidence that these populations have been driven by antigen. The results suggest that the selective and massive expansion of a few dominant clones of CD8+ T cells is an important feature of the primary response to this virus.

Modulation of promiscuous T cell receptor recognition by mutagenesis of CDR2 residues

The T cell receptor (TCR) recognizes a ligand composed of a major histocompatibility complex (MHC) molecule and a peptide antigen. Prior studies of murine T cell clones have demonstrated that residues in the CDR3 region of TCR interact with amino acids in the peptide during MHC-restricted antigen recognition. However, the questions of whether direct TCR MHC contacts are made and where such contact sites might map in the TCR have not been resolved. In this study, we have taken advantage of the promiscuous recognition of a peptide from influenza virus (HA 307-319) by human T cell clones to map sites in the TCR that mediate differences in human leukocyte antigen-D related (HLA-DR) restriction in the presence of a common peptide antigen. Site-specific mutagenesis of cloned TCR genes and transfection into Jurkat cells were used to demonstrate that single amino acid substitutions in CDR2 of the TCR-alpha chain controlled whether a T cell was restricted by the product of a single DR allele (DR7) or would respond to the HA 307-319 peptide when presented by the products of one of several different DR alleles (DR1, DR4, DR5, or DR7). Because the relevant DR alleles are defined by polymorphism in the DR-beta chain, these results also suggest a rotational orientation for recognition in which TCR-alpha interacts with DR beta.

Selection of T cell receptor variable gene-encoded amino acids on the third binding site loop: a factor influencing variable chain selection in a T cell response

The 3' end of the T cell receptor V beta 7.1 gene contains the five nucleotides CAAGA between the broadly conserved consensus sequence of nucleotides TGC/T GCC AGC AGC (which encode cysteine, alanine, serine and serine at positions 92-95 of the beta chain) and the heptamer that signals rearrangement. These nucleotides are frequently preserved during gene rearrangement, resulting in the common presence of glutamine at position 96 and of aspartate or glutamate at position 97 of the V beta 7.1 chain CDR3 loop in peripheral blood lymphocytes. There is selection of V beta 7.1 and of the V beta 7.1 gene-encoded glutamate at position 97 of the beta chain CDR3 loop in the cytotoxic T lymphocyte response to the HLA B2705-restricted influenza A nucleoprotein epitope SRYWAIRTR. Our results indicate that selection of V beta 7.1 gene-encoded amino acid residues on CDR3 loops may be one factor driving selection of V beta 7.1 in this response.

T cell receptor repertoire in polymyositis: clonal expansion of autoaggressive CD8+ T cells

In polymyositis (PM), CD8+ T cell receptor (TCR) alpha/beta + cells invade and destroy major histocompatibility complex class I-positive muscle fibers. We combined polymerase chain reaction (PCR) and double-fluorescence immunocytochemistry to analyze the T cell receptor (TCR) repertoire expressed in muscle of PM patients. In patient 1, inverse PCR revealed a preferential usage of TCR V alpha 33.1, V beta 13.1, and V beta 5.1. Six of six TCR V alpha 33.1+ clones and five of seven V beta 13.1+ clones had identical nucleotide sequences. In contrast, the V beta 5.1+ TCRs were more heterogeneous. Similar results were obtained with an independent PCR method using primers specific for TCR V alpha 33, V beta 13, or V beta 5. No TCR sequences could be amplified from noninflammatory control muscle. Furthermore, none of the TCR sequences found in PM muscle could be detected in blood from the same patient or from a normal control subject. Immunohistochemistry confirmed that V beta 5.1 and V beta 13.1 were overrepresented in the muscle lesions of this patient. 32% of all CD8+ T cells were V beta 13.1+, and 16% were V beta 5.1+. However, approximately 60% of the CD8+ T cells that invaded muscle fibers were V beta 13.1+, whereas 10% were V beta 5.1+. In patient 2, 50% of the T cells were V beta 5.1+, and as in patient 1, these T cells were mainly located in interstitial areas. In patient 3, > 75% of the autoinvasive T cells stained with an anti-V beta 3 mAb. Sequence analysis of 15 PCR clones amplified with a V beta 3-specific primer showed that 9 (60%) sequences were identical. The results suggest that (a) a strikingly limited TCR repertoire is expressed in PM muscle; (b) there is a dissociation between the TCR usage of autoinvasive and interstitial T cells; and (c) the autoinvasive T cells are clonally expanded.

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.

Analysis of the T-cell receptor beta-chain variable-region (V beta) repertoire in monozygotic twins discordant for human immunodeficiency virus: evidence for perturbations of specific V beta segments in CD4+ T cells of the virus-positive twins

We analyzed the T-cell receptor (TCR) V beta repertoire in human immunodeficiency virus type 1 (HIV-1)-infected individuals at different stages of disease. To circumvent the effect of HLA and other loci on the expressed TCR repertoire, we compared the TCR repertoire in nine pairs of monozygotic twins who were discordant for HIV infection. A semiquantitative polymerase chain reaction (PCR) assay and flow cytometry enabled us to show distinct differences in the V beta repertoire in the HIV-positive twin compared with the HIV-negative twin. By combining PCR and cytofluorometry, these differences were restricted to a specific set of TCR V beta segments, with members of the V beta 13 family perturbed in six out of seven cases and those of the V beta 21 family perturbed in four out of seven cases studied. Most of the other V beta families remained unchanged. Our results provide direct evidence for a skewed TCR repertoire in HIV infection.

Clonal populations of T cells in normal elderly humans: the T cell equivalent to "benign monoclonal gammapathy"

To determine whether T cells, like B cells, can become clonally expanded in normal individuals as a function of age, we compared the T cell V beta repertoire of cord blood to that of peripheral blood from normal donors over 65 yr of age. T cells from elderly subjects contained expanded subsets (greater than the mean+three standard deviations) of T cell receptor (TCR) V beta populations. These expanded subsets were observed primarily among CD8, but not CD4 cells, represented up to 37.5% of all CD8 cells, and were present in most elderly subjects. An expanded V beta 5.2/3 CD8 subset and a V beta 6.7a CD8 subset from separate donors were analyzed by reverse transcriptase-polymerase chain reaction, cloning and sequencing of the TCR beta chain VDJ junction. In both cases the expanded subsets were mono- or oligoclonal while control CD4 populations were polyclonal. Using two-color flow cytometry it was possible to identify the expanded V beta 6.7a subset as CD8+ CD28-CD11b+ cells. In three of five random old subjects similar expansions of V beta subsets were found specifically in the CD8+ CD28- subpopulation, an interesting subset of cytotoxic T lymphocytes, known to lack proliferative responses to TCR stimuli. It is common practice to use the demonstration of clonality as a diagnostic indicator for T cell lymphoma/leukemia. In view of the high frequency of expanded T clones of T cells in normal elderly subjects the diagnostic usefulness of this test should be reexamined.

Bovine x murine T-cell hybridomas specific for bovine herpesvirus 1 (BHV-1) glycoproteins

Difficulties in the isolation and long-term maintenance of bovine herpesvirus-1 (BHV-1) specific T-cell clones have hindered the analysis of bovine cell-mediated immune response to this virus. In an effort to identify the T-cell epitopes of the virus, bovine murine T-cell hybridomas specific for BHV-1 were generated as an alternative to T-cell clones. Peripheral blood lymphocytes from a calf immunized with BHV-1 were restimulated in vitro with the virus to generate bulk T-cell cultures. The antigen-specific T-cell-enriched bulk culture lymphocytes were fused with the T-cell receptor-deficient mutant of the murine thymoma cell line BW 5147. T-cell hybridomas were screened for their ability to produce interferon-gamma in response to BHV-1 stimulation. Hybridomas with various specificities were obtained. One of them was specific for the BHV-1 glycoprotein gI, two were specific for gIV, while three other hybridomas were specific for gIII. One hybridoma responded to stimulation with BHV-1, but not to any of the glycoproteins gI, gIII, or gIV, suggesting that proteins other than these major glycoproteins may be involved in the bovine T-cell response to BHV-1. Of these hybridomas, one was MHC Class I restricted, while all the others were Class II restricted.

A method for producing monoclonal antibodies to human T-cell-receptor beta-chain variable regions

Study of the T-cell repertoire in humans has been hampered by the lack of monoclonal antibodies (mAbs) to the T-cell receptor (TCR) variable region (V) gene products. We describe a method for producing mAbs to the human TCR beta-chain V (V beta) gene products in which mice were immunized with a rat basophil cell line (RBL-2H3) transfected with the extracellular domain of the TCR heterodimer fused to the lambda chain of CD3. These cells acted as excellent immunogens for raising anti-TCR mAb and also formed the basis of a rapid screening assay. We generated mAbs against V beta protein of the TCR, showed that these mAbs stained approximately 1% of peripheral blood T cells, and further showed that the mAbs could stimulate proliferation of these T cells. We then characterized the mAbs by amplifying TCR cDNA derived from mAb-stimulated cells and sequencing the beta chain. All clones sequenced used the V beta 7.1 chain, proving conclusively that the mAbs generated were specific for V beta 7.1 subfamily. This method generates mAbs to human TCR V beta proteins efficiently and might allow production of a complete panel of mAbs directed against human TCR V beta proteins.

Human Tcrb-V6.10 is a pseudogene with Alu repetitive sequences in the promoter region

Tcrb-V6.10 represents an abnormal human V gene with an Alu insertion in the promoter, a point mutation of a conserved Cys at position 23, and a missing nonamer within the usually conserved recombinase signal sequence. Here it is shown that b-V6.10 is found in the genome of most individuals, is normally located in the Tcrb-V locus on chromosome 7, but is not rearranged or transcribed. Thus, it is likely that the abnormal signal sequence precludes recombination and that the Alu insertion results in a disabled promoter, indicating the functional importance of the affected regions. Tcrb-V6.10 probably evolved by duplication of an ancestral Tcrb V13-V6-V5 cassette, like other members of the large b-V6 subfamily, and more recently became inactivated into a pseudogene.

Generation of monoclonal antibodies against a human T cell receptor beta chain expressed in transgenic mice

The generation of a panel of monoclonal antibodies specific for different variable (V) regions of human T cell receptors will be of great importance in the study of T cell-mediated diseases. However, relatively few such reagents exist, due in part to the poor immunogenicity of TcRs on the surface of human T cells. We have employed a strategy in which T cells from a transgenic mouse line expressing a human V beta 3 C beta 1 TcR were used to immunise syngeneic conventional mice to generate two monoclonal antibodies specific for human T cell receptors. Binding of antibody JOVI.3, which stained approximately 5% of human peripheral blood CD3 positive T cells, correlated with the expression of the human TcR V beta 3 gene segment. Antibody JOVI.1 recognised a determinant on the majority of TcRs, staining 50-75% of peripheral blood T cells and T cell lines expressing different V beta regions. Some TcRs, however, failed to react with this antibody. Both antibodies immunoprecipitated detergent-solubilised TcR molecules and were capable of inducing proliferation of peripheral blood T cells.

A versatile method to produce antibodies to human T cell receptor V beta segments: frequency determination of human V beta 2+ T cells that react with toxic-shock syndrome toxin-1

Human V beta (hV beta) regions have been expressed in the context of mouse T cell receptor (TcR)-CD3 complexes, and subsequently used to raise hV beta-specific monoclonal antibodies (mAb). The method of expression of hV beta outlined in this report contrasts in its versatility with the one reported by Choi et al. (Proc. Natl. Acad. Sci. USA 1991. 88: 8357). For instance, we have applied it successfully to the construction of mouse T cell transfectants expressing hV beta 1, hV beta 2, hV beta 3, hV beta 8, hV beta 9, hV beta 13.5, hV beta 19, hV beta 21, and hV beta 22 gene segments. mAb against the hV beta 2 and hV beta 19 regions have been raised by using these transfectants as immunogens in mice. Here, we illustrate the application of the anti-hV beta 2 mAb to the measurement of human T cells that react with the staphylococcal toxic-shock syndrome toxin-1.

Predominant use of a T-cell receptor V beta gene family in simian immunodeficiency virus Gag-specific cytotoxic T lymphocytes in a rhesus monkey

To explore the structural basis for AIDS virus recognition by CD8+ lymphocytes, we sought to determine whether there is a diverse or restricted usage of T-cell receptors (TCR) by simian immunodeficiency virus of macaques (SIVmac) Gag-specific cytotoxic T lymphocytes (CTL) in the rhesus monkey. Six Gag-specific CTL clones were independently generated from an SIVmac-infected rhesus monkey. All six CTL clones recognized a single SIVmac Gag peptide in association with a single major histocompatibility complex class I gene product, Mamu-A*01. TCR alpha-chain sequences from these six CTL clones employed four different V alpha families and five different J alpha gene segments. In contrast, five of the six CTL clones expressed V beta genes that were members of the same family, a human V beta 23 homolog. Furthermore, only one J beta gene was expressed by four of the six CTL clones. These results indicate that TCR of SIVmac Gag-specific CTL from a rhesus monkey can exhibit a restricted usage of V beta gene families and J beta genes.