T-cell receptor beta-chain gene usage in the T-cell recognition of Mycobacterium leprae antigens in one tuberculoid leprosy patient

Etiology of sarcoidosis

Since sarcoidosis was first recognized as a distinct clinical entity, investigators have speculated that a transmissible agent may cause sarcoidosis. Recent attempts at directly isolating infectious organisms or indirectly detecting microbial DNA or RNA from sarcoid tissue have led to inconclusive results. Studies on the immunopathogenic origins of sarcoidosis have provided evidence of persistent antigenic stimulation at sites of inflammation that are associated with dysregulated cytokine production. To date, however, the challenge of defining the cause of sarcoidosis remains unmet.

Human immunodeficiency virus type 1 Nef does not alter T-cell sensitivity to antigen-specific stimulation

We have developed an in vitro model to study the influence that human immunodeficiency virus type 1 (HIV-1) may have on the ability of T cells to respond to antigenic challenge. We have examined consequences of HIV-1 gene expression on T-cell activation in antigen-dependent T cells that have stably integrated copies of replication-defective proviral HIV-1. Virus production by HIV-infected, antigen-dependent T cells was induced in response to antigenic stimulation and then decreased as infected cells returned to a state of quiescence. Contrary to the predictions of models proposing that Nef alters signal transduction pathways in T lymphocytes and thereby alters cellular activation, Nef expression in antigen-dependent T-cell clones did not influence their proliferative responses to low or intermediate concentrations of antigen and did not affect other measures of T-cell activation, such as induction of interleukin 2 receptor alpha-chain expression and cytokine production. In addition, we found no evidence for alteration of T-cell responsiveness to antigen by the gag, pol, vif, tat, or rev gene of HIV-1.

Limited heterogeneity of biased T-cell receptor V beta gene usage in lung but not blood T cells in active pulmonary sarcoidosis

Sarcoidosis is a multisystem disorder characterized by non-caseating granulomas and the accumulation of CD4+ T cells in involved tissues such as the lung. To evaluate the diversity of the CD4+ T-cell repertoire in this disorder, a detailed clonal analysis was performed in five individuals with active sarcoidosis who demonstrated preferential accumulation of T cells expressing the T-cell receptor variable gene family V beta 8 in either the lung or blood. In three individuals, analysis of unselected samples of nucleotide sequences derived from V beta 8+ lung T cells demonstrated degrees of clonality ranging from 11% to 46%, indicating the expansion of limited numbers of V beta 8+ T-cell clones in the lung. Analysis of the corresponding deduced amino acid sequences demonstrated common VDJ junctional amino acid residues in the dominant V beta 8+ T-cell clones derived from two oligoclonal V beta 8+ lung T-cell populations, consistent with an antigen-specific T-cell response. In contrast, analysis of V beta 8+ CD4+ T cells from the blood of an individual with a marked bias for peripheral blood V beta 8+ T cells demonstrated no evidence of oligoclonality, suggesting that the stimulus for circulating biased V beta-specific T cells in sarcoidosis may derive from a different, perhaps superantigenic, origin. Clinical improvement in the disease either in response to treatment with corticosteroids or as a result of spontaneous resolution was associated with a decrease in the proportion of V beta 8-specific T cells in the biased lung and/or blood T-cell compartments. Together, these observations are consistent with a role for this T-cell subset in the clinical manifestations of active granulomatous disease.

Biased T cell receptor V gene usage in tissues with periodontal disease

In an attempt to characterize TCR V gene usage in human periodontally diseased tissue, V alpha 2, V beta 5.2-3, V beta 5.3, V beta 5.1, V beta 6.7, V beta 6.7, V beta 8 and V beta 12.1 expressions were examined. Serial cryostat sections obtained from 20 periodontitis and 9 gingivitis biopsies were then reacted with monoclonal antibodies directed to each repertoire. The technique was combined with a sensitive alkaline phosphatase-anti-alkaline phosphatase method. Peripheral blood was obtained from 10 periodontitis and 2 gingivitis patients. TCR repertoire was also quantified by flow cytofluorography with FITC-conjugated antibodies. Cells displaying binding of each antibody were counted. The proportions to CD3-positive cells were then calculated. The pattern of each TCR V gene product expression in inflamed gingiva exhibited individual variation, nevertheless, a consistent pattern emerged. The V beta 5 subfamily and V beta 6.7 were frequently used repertoires in gingiva, whereas the V alpha 2 and V beta 8 subfamily were underexpressed in most cases. Furthermore, the TCR V gene product expression in gingival tissue was biased compared with autologous peripheral blood. Three of 10 periodontitis subjects showed 1 or 2 strikingly overrepresented repertoire comparatively with autologous blood. In these 3 subjects V beta 6.7 was overexpressed in two cases and 5.2-3, V beta 8 and V beta 12.1 were overexpressed in one case. These results suggest that gingival T-cells are not randomly mobilized from peripheral blood and that local events influence the TCR repertoire at the level of T-cell recruitment or T-cell expansion.

T cell receptor (TCR) repertoire in alloimmune responses

A large number of alloantigenic determinants could be generated by both the direct and indirect alloantigen presentation pathways. Hence, a heterogeneous population of T cells expressing a wide variety of receptors would be expected to respond to this diverse array of alloantigenic determinants. However, T cells expressing highly restricted T cell receptor (TCR) variable genes have been reported in a variety of alloimmune responses. A similar phenomenon has been observed in a wide variety of other immune responses, from those induced by superantigens, to very specific responses induced by a single peptide presented by a single MHC molecule. Given this scenario, the limited number of T cell clones which dominate an allograft rejection response, or for that matter an autoimmune response or a tumor specific response, could be therapeutically targeted by virtue of the selected TCR expression.

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.

Therapeutic regulation of T cells in rheumatoid arthritis

TCR repertoire studies in RA have yielded conflicting data. These studies were initiated on the premise that clonal expression of T cells at the site of inflammation could serve as a target for immune therapies designed on the basis of the option to inactivate or eliminate the presumed pathogenic T cells. These analyses have demonstrated the existence of a highly diverse overall TCR repertoire on the basis of extensive usage of TCR V genes both in synovial fluid and tissue. However, clusters of RA patients can be recognized who share increased usage frequencies of defined TCR V genes among synovial fluid or synovial tissue lymphocytes. Subsequent analysis of the CDR3 regions among diverse overall TCR repertoires have revealed the presence of conserved amino acid sequences in the CDR3 regions of the variable portions of TCRs in T lymphocytes derived from the site of inflammation. These findings suggest that a selective, antigen-driven expansion of T lymphocytes is occurring in the inflamed joints. Parallel to the TCR-repertoire studies, we investigated whether vaccines prepared from synovial T cells could modulate T-cell reactivity. The studies were based on previous work on TCV in animals, revealing that attenuated non-specific T-cell lines could serve as a vaccine. The results obtained in 13 RA patients showed no clear indication for a cellular or humoral immune response. Our experience with TCV in RA patients showed that this technique is feasible and safe. We found some evidence for a modulated T-cell reactivity both in vivo and in vitro. These results show at least some immunomodulatory effect af T-cell vaccination, although the antigen specificity of the effect of this intervention remains to be shown. Because of the convincing studies in animals and MS patients, further studies in RA should focus on the effect of vaccination using vaccines prepared from disease-inducing cells. In this respect, determination of the CDR3 regions of synovial T cells could lead to the identification of those T cells that are relevant for the disease.

An HLA-DRw53-restricted T-cell epitope from a novel Mycobacterium leprae protein antigen important to the human memory T-cell repertoire against M. leprae

Cellular immunity mediated by T cells plays a major role in protection against intracellular infections, including leprosy, a chronic disease caused by Mycobacterium leprae. In this work, we describe CD4+ T-cell clones, isolated from healthy humans immunized with M. leprae, which recognize a novel M. leprae protein antigen previously isolated from a lambda gt11 DNA expression library. On the basis of the deduced primary structure of the carboxyl-terminal part of the antigen, we have used a synthetic-peptide approach to exactly define the T-cell epitope recognized. Importantly, major histocompatibility complex restriction studies showed that the epitope is presented by an HLA-DRw53 molecule which is frequently expressed in many populations. In addition, we have demonstrated that a long-term cell-mediated immunity response against the peptide epitope is present after immunization with M. leprae. In conclusion, the M. leprae T-cell epitope described here fulfills the primary criteria for subunit vaccine candidates against leprosy.

Increased frequency of V beta 17-positive T cells in patients with rheumatoid arthritis

OBJECTIVE

To identify the T lymphocytes that mediate disease in rheumatoid arthritis (RA).

METHODS

A panel of monoclonal antibodies reactive with T cell receptor (TCR) V beta gene products was used to analyze the RA T cell repertoire.

RESULTS

Of 5 TCR V beta gene products studied, only V beta 17-positive T cells were increased in peripheral blood and synovial fluid (SF) from RA patients, compared with controls (P < 0.01 and P = 0.0006, respectively). Thirty-one percent of the 49 RA SF samples and none of the 19 non-RA SF samples contained > 10% V beta 17-positive T cells. Activated (Tac-positive) T cells were enriched among V beta 17-positive synovial T cells.

CONCLUSION

The selective increase of V beta 17-positive T cells suggests a role for those T cells in the pathogenesis of RA.

Selective activation and accumulation of oligoclonal V beta-specific T cells in active pulmonary sarcoidosis

Sarcoidosis is a granulomatous disease in which activated T cells, responding to an unidentified stimulus, accumulate at sites of disease such as the lung. To evaluate the hypothesis that active sarcoidosis is characterized by a selective activation and expansion of a limited repertoire of T cell receptor (TCR) specific T cells, we analyzed TCR V beta gene expression in lung and blood T cells of patients with active sarcoidosis and, for comparison, normal individuals using polymerase chain reaction amplification of 20 V beta gene families. Analysis of normal bronchoalveolar lavage T cells revealed TCR V beta distributions similar to that of normal blood, providing evidence for a lack of generalized skewing of the T cell repertoire in the normal, noninfected lung. Compared to normal lung and blood, subgroups of individuals with sarcoidosis demonstrated biased expression of one or more V beta genes in either the lung or blood. Five V beta gene families (V beta 5, V beta 8, V beta 15, V beta 16, and V beta 18) were most frequently utilized in a biased fashion by sarcoid lung or blood T cells. Furthermore, dramatic skewing of the T cell repertoire was apparent when sarcoid lung and blood T cells were expanded by short-term culture with IL-2. Sequence analysis demonstrated a bias in V beta gene expression was usually due to expansion of select V beta-specific clones, some of which contained a similar V(D)J junctional region motif. These observations provide evidence for a selective activation and accumulation of antigen-specific V beta-expressing T cells in sarcoidosis.

Association between HLA-DQB1 alleles and risk for cervical cancer in African-American women

Squamous-cell carcinoma of the cervix and its precursor lesions are associated with human papillomavirus (HPV) infection. Epidemiological studies indicate that HPV infection in itself is not sufficient for cervical-cancer induction, suggesting that other factors contribute to carcinogenesis. We have investigated the potential role of host genetic background as one such factor. We screened a series of squamous-cell carcinomas of the cervix for HLA-class-II DQB1* alleles by the polymerase chain reaction and site-specific oligonucleotide probe hybridization and for HPV type from African-American women using a local, ethnically matched control panel. Statistically significant associations for increase in relative risk for cervical cancer were seen for DQB1*0303 and DQB1*0604. DQB1*0201 and the heterozygote DQB1*0301/*0501 showed a decrease in relative risk for cervical cancer. HPV typing revealed no association between virus type and DQB1 alleles. Our results confirm other studies showing an increase in relative risk for cervical cancer associated with HLA-DQ3 alleles in Caucasians.

Characterization of the primary structure of T cell receptor beta chains in cells infiltrating the salivary gland in the sicca syndrome of HIV-1 infection. Evidence of antigen-driven clonal selection suggested by restricted combinations of V beta J beta gene segment usage and shared somatically encoded amino acid residues

Infection with HIV-1 occasionally results in a sicca syndrome, termed the diffuse infiltrative lymphocytosis syndrome, characterized by infiltration of the salivary glands with a predominance of CD8 T cells. This response is strongly associated with certain MHC class I and class II alleles. To define the salivary gland T cell receptor (TCR) repertoire, the primary structure of the TCR beta-chains was determined using in situ cDNA synthesis followed by the "anchored" polymerase chain reaction. The sequences of 59 beta-chains from five individuals with diffuse infiltrative lymphocytosis syndrome shared structural features suggesting antigenic clonal selection. Certain combinations of V beta J beta gene segments were selectively overrepresented in the repertoire sample, demonstrating a common restricted usage of certain V beta and J beta gene segments. The beta-chains derived from these overrepresented V beta J beta combinations revealed a preference for specific amino acids at position 97 in the third complementarity-determining region, a residue postulated to contact peptide antigen. Moreover, the nucleotides encoding this position were not germline in origin. TCR beta-chains in nonoverrepresented V beta J beta combinations did not exhibit preferential usage of selected somatically encoded residues. The pattern of TCR beta-chains expressed in the salivary gland of a control person with primary Sjögren's syndrome was considerably more heterogeneous and different from that found in diffuse infiltrative lymphocytosis syndrome.

Restricted T cell receptor expression by human T cell clones specific for mycobacterial 65-kDa heat-shock protein: selective in vivo expansion of T cells bearing defined receptors

We have examined the T cell receptor (TcR) expression of clones specific for epitopes of mycobacterial 65-kDa heat-shock protein (hsp65) in the context of two different HLA molecules, and used this system as a model to assess the selection of T cells responsive to this antigen in vivo. DR3-restricted clones were raised from both the synovial fluid (SF) and peripheral blood (PB) of a patient with reactive arthritis in three separate cloning events. Five of five SF-derived clones tested expressed either V beta 5.2 or a closely related beta chain, V beta 5.6. The alpha chains expressed by V beta 5.2+ and V beta 5.6+ clones were from different families, V alpha 2.4 and V alpha 23.2, respectively. Nine of ten clones derived from two cloning procedures on PB taken 3 years later also expressed either V beta 5.2 or V beta 5.6. This suggests that the TcR repertoire for recognizing this major histocompatibility complex/peptide complex is relatively restricted and favors the use of V beta 5. Conservation of the beta chain third complementarity-determining region (CDR3) sequence was not evident, however. Sequencing alpha and beta chains of representative V beta 5.2+ and V beta 5.6+ PB-derived clones revealed TcR which were identical to those utilized by the SF-derived clones, showing that the repertoire for recognition of this antigen is stable over time. Similar studies of TcR expression were carried out on hsp65-specific, DP4-restricted clones derived from the SF of a patient with rheumatoid arthritis by two independent cloning procedures. There was conservation of alpha chain usage, since all clones expressed a member of the V alpha 1 family, but again CDR3 sequence conservation was not apparent. beta chain usage was not restricted since different clones expressed V beta 6.7, V beta 22.3 and V beta 12. Subtle differences in epitope specificity were detected for two clones with differing TcR. Once more, T cell clones with identical alpha and beta TcR chains were obtained from the separate cloning procedures, suggesting oligoclonalty of T cells with this defined specificity in the patient's SF.