Expression of T-cell Receptor (TCR)α Chain on Normal Human Tonsils and T-cell Lymphomas

We analyzed immunohistologically the expression of T cell receptor (TCR)α chain on human tonsils and on T cell lymphoma (T ML) tissues using the avidin biotin peroxidase method. A murine monoclonal antibody αF1, specific for the constant region of the JCRα chain, was employed. On normal tonsil, αF1 positive cells were observed mainly in T zones and germinal centers. In T zones, the staining intensities varied markedly, with heavy staining evident in less than one fourth. In germinal centers, a proportion of stained cells showed a histiocytic pattern with small cytoplasmic projections. All the T ML tissues expressed TCRα, whereas the staining intensities varied among cases and among lymphoma cells. No correlations were observed in the expressions of TCRα chain and other T-cell markers including CD3, CD4 and CD8. Acta Pathol Jpn 40: 722-728, 1990.     

T-cell receptor repertoire of human peripheral CD161hiTRAV1-2+ MAIT cells revealed by next generation sequencing and single cell analysis

Mucosal-associated invariant T (MAIT) cells are a T-cell subset that expresses a conserved TRAV1-2 (Vα7.2) T-cell receptor (TCR) chain and the surface marker CD161. They are involved in the defence against microbes as they recognise small organic molecules of microbial origin that are presented by the non-classical MHC molecule 1 (MR1). MAIT cells express a semi-restricted TCR α chain with TRAV1-2 preferentially linked to TRAJ33, TRAJ12, or TRAJ20 which pairs with a limited set of β chains. To investigate the TCR repertoire of human CD161^hiTRAV1-2⁺ T cells in depth we analysed the α and β chains of this T-cell subset by next generation sequencing. Concomitantly we analysed 132 paired α and β chains from single cells to assess the αβ pairing preferences. We found that the CD161^hiTRAV1-2⁺ TCR repertoire in addition to the typical MAIT TCRs further contains polyclonal elements reminiscent of classical αβ T cells.     

Integrated morphogen signal inputs in γδ versus αβ T-cell differentiation

Summary:  Morphogens, a class of secreted proteins that regulate gene expression in a concentration-dependent manner, are responsible for directing nearly all lineage fate choices during embryogenesis. In the thymus, morphogen signal pathways consisting of WNT, Hedgehog, and the transforming growth factor-β superfamily are active and have been implicated in various developmental processes including proliferation, survival, and differentiation of maturing thymocytes. Intriguingly, it has been inferred that some of these morphogen signal pathways differentially affect γδ and αβ T-cell development or maintenance, but their role in T-cell lineage commitment has not been directly probed. We have recently identified a modulator of morphogen signaling that significantly influences binary γδ versus αβ T-cell lineage diversification. In this review, we summarize functions of morphogens in the thymus and provide a highly speculative model of integrated morphogen signals, potentially directing the γδ versus αβ T-cell fate determination process.     

γδ T-cell receptors: functional correlations

Summary:  The γδ T-cell receptors (TCRs) are limited in their diversity, suggesting that their natural ligands may be few in number. Ligands for γδTCRs that have thus far been determined are predominantly of host rather than foreign origin. Correlations have been noted between the Vγ and/or Vδ genes a γδ T cell expresses and its functional role. The reason for these correlations is not yet known, but several different mechanisms are conceivable. One possibility is that interactions between particular TCR-V domains and ligands determine function or functional development. However, a recent study showed that at least for one ligand, receptor specificity is determined by the complementarity-determining region 3 (CDR3) component of the TCR-δ chain, regardless of the Vγ and/or Vδ. To determine what is required in the TCR for other specificities and to test whether recognition of certain ligands is connected to cell function, more γδTCR ligands must be defined. The use of recombinant soluble versions of γδTCRs appears to be a promising approach to finding new ligands, and recent results using this method are reviewed.     

Characterization of T-Cell Receptor αβ Repertoire in Synovial Tissue from Different Temporal Phases of Rheumatoid Arthritis

The role of protein kinase C (PKC) in TNF alpha-induced activation of endothelial adhesion molecules ICAM-1 and VCAM-1 was analysed. Phorbol myristate acetate, which is known to activate PKC, was able to mimic TNF alpha-induced up-regulation of ICAM-1 and partly also VCAM-1 expression. Similarly a PKC inhibitor, H7, but not another kinase inhibitor, HA1004, inhibited TNF alpha-induced enhancement of ICAM-1 expression at both the mRNA and the protein level. Moreover we were able to measure a transient PKC activation peak at 16 min after TNF alpha induction in endothelial cells analysed by phorbol-dibutyrate binding. These results indicate that the TNF alpha-induced effect on the regulation of endothelial adhesion molecule expression is at least partly mediated by PKC activation.     

The role of the T-cell receptor (TCR) in αβ/γδ lineage commitment: clues from intracellular TCR staining

Summary: T cells belong to two mutually exclusive lineages expressing either αβ orγδ T-cell receptors (TCR). Although αβ and γδ cells are known to share a common precursor the role of TCR rearrangement and specificity in the lineage commitment process is controversial. Instructive lineage commitment models endow the αβ or γδ TCR with a deterministic role in lineage choice, whereas separate lineage models invoke TCR-independent lineage commitment followed by TCR-dependent selection and maturation of αβ and γδ cells. Here we review the published data pertaining to the role of the TCR in αβ/γδ lineage commitment and provide some additional information obtained from recent intracellular TCR staining studies. We conclude that a variant of the separate lineage model is best able to accommodate all of the available experimental results.     

αβ and γδ T-cell networks and their roles in natural resistance to viral infections

Summary: Lymphocyte-mediated inflammation is a hallmark of autoimmune diseases, such as multiple sclerosis, Crohn's disease, rheumatoid arthritis and sarcoidosis. However, this type of inflammation probably developed under evolutionary pressure from pathogenic microorganisms, such as mycobacteria and other intracellular infective agents. One such pathogen, the gram-positive bacterium Listeria monocytogenes (L. monocytogenes), induces a cascade of tissue alterations that ultimately results in the eradication of the bacteria associated with a granulomatous response. Consequently, murine listeriosis has been established as a model to analyze not only T-cell-dependent antibacterial protection but also T-cell-mediated mononuclear inflammation in parenchymal organs. Extensive studies of the molecular basis of the latter phenomenon led to the conclusion that the most decisive step from non-specific microabscess formation to granulomatous inflammation is the activation of non-specifically invading CD4⁺ T cells, which results in high local concentrations of TNF-α and IFN-γ in the presence of IL-2. This in turn induces CD11b-independent mechanisms of intraparenchymal monocyte accumulation. Because any attempt to neutralize the effects of TNF-α and IFN-γ to modulate T-cell-mediated inflammation will also dramatically decrease host resistance, other anti-inflammatory strategies based on the modulation of TNF-α and IFN-γ-induced mechanisms of monocyte accumulation must be developed. Recalling the classical work by Dienes & Schoenheit on the induction d bacterial allergies (1), the cytokine phenotype of granuloma formation also has implications as regards the most potent adjuvant environment for the development of a T-cell response. The murine listeriosis model is the basis for all conclusions in this article on the role of cytokines in the induction and expression of T-cell-mediated inflammation and. as we will show, promises to yield still more insights into the rational design of vaccines.     

Emergence of α5β1 fibronectin- and αvβ3 vitronectin-receptor expression in melanocytic tumour progression

Cell adhesion is crucial in the process of tumour progression. As integrins are important receptor molecules involved in cell adhesion, we studied the distribution of the α1-6, αv, αIIb, β1, β3, and β4 integrin subunits in tissue sections of common naevocellular naevi ( n =22), dysplastic naevi (16), thin (24) and thick primary cutaneous melanomas (28), and melanoma metastases (25). We found correlated expression of α1/α2, of α4/α5/β3, and of α6/β4. Decrease of α6 and β4, and increase of α4 and αv were found to be correlated with melanoma progression. Furthermore, expression of α5 and β3 was detected only in primary melanoma and melanoma metastasis. Our findings indicate that during melanoma progression alterations in integrin expression occur, the most striking being emergence of α5β1 fibronectin and αvβ3 vitonectin receptor.     

Characterization of T-cell subsets and T-cell receptor subgroups in pigtailed macaques using two- and three-color flow cytometry

In order to characterize macaque T-lymphocyte subsets, we used a chromophore from a dinoflagellate, peridinin chlorophyll A protein (PerCP), which, like fluorescein isothiocyanate (FITC) and R-phycoerythrin (PE), can be excited by a 488-nm laser and emits light at 670 nm without spectral overlap with FITC and PE. Mouse monoclonal antibodies were conjugated with FITC, PE, and PerCP to detect CD4+ and CD8+ cells in macaque peripheral blood lymphocytes (PBL) subsets before and after activation and in nonactivated thymocytes. Resting and activated macaque blood CD4+ T-cells could be clearly delineated into discrete subsets with either CD28, CD45RA, or CD45RO as a second marker and CD26, CD29, CD44, or CD69 as a third marker. CD8+ cells were further subdivided by expression of similar combinations of markers. A subset of CD8+ CD28– T-cells in blood expressed the activation marker CD69, suggesting that they were already activated. Virtually all CD4+CD8+, CD4+CD8–, and CD4–CD8+ macaque thymocytes expressed CD2, CD3, and CD18 and not CD25, CD44, or CD45O, but macaque thymocyte subpopulations did differ in their expression of CD28 and CD29. The expression of T-cell receptor (TCR) subgroups on macaque PBL and thymocytes was analyzed before and after activation with staphylococcal enterotoxins (superantigens). The pattern of T-cell variable-region expression in macaques was similar to that seen in humans, with a high frequency of T cells expressing V8. After superantigen stimulation, only minor changes in TCR V expression were detectable in PBL. A dramatic increase in V8 expression was seen after stimulation of macaque thymus with staphylococcal enterotoxin D (SE-D), a minor increase after toxic shock syndrome toxin 1 (TSST-1) stimulation, and a simultaneous decrease in V6 levels.     

T-cell receptor variable (V) gene usage by lymphoid populations in T-cell lymphoma.

A panel of monoclonal antibodies specific for TcR V gene families was used to study TcR V region expression in 28 cases of malignant and reactive T-cell expansions including four cases of mixed cellularity Hodgkin's disease (HD) and five reactive cases. TcR V beta 5 gene products were represented in three cases of lymphoblastic malignancy (V beta 5.1, V beta 5.2) and two cases of peripheral T-cell lymphoma (PTCL) (V beta 5.1). In the PTCL cases, the expanded family was found in the absence of clonal TcR gene rearrangements and in one of these cases with Ig JH and Ck clonal gene rearrangements consistent with the presence of a phenotypically and histologically undetectable clonal B-cell population. In a third PTCL case not investigated for genotype, the TCR V alpha 12 family was overrepresented. Expanded TcR V alpha 2 and V beta 5.1 families were identified in HD and V beta 8 and V beta 5.2/V beta 5.3 families in a reactive lymph node and CD3 and CD8-positive blood lymphocytosis respectively. Further study of PTCL and related entities are needed to establish whether expanded TcR families are common in those cases that fail to exhibit clonal TcR gene rearrangement.     

Changes in airway responsiveness and β- and α-adrenergic receptors in the lungs of guinea pigs with experimental asthma

The effects of inhaled allergen on airway responsiveness and on beta- and alpha-1-adrenergic receptors on lung membrane were investigated in guinea pigs. After measuring the respiratory threshold to histamine (RT-HIS), one group of guinea pigs passively sensitized for ovalbumin was challenged by allergen inhalation (challenged group). Measurement of the RT-HIS 24 h following challenge revealed a significant decrease from 687 micrograms/ml (mean, n = 16) to 407 micrograms/ml (P less than 0.05). In addition the RT-HIS 24 h after challenge was also significantly lower in the challenged group than in controls (n = 9, P less than 0.05). The density of beta-adrenergic receptors on the lung membrane of the challenged group was 594 +/- 32 (mean +/- SE) fmol/mg protein (n = 11) compared with 712 +/- 24 fmol/mg protein (n = 9) in the controls, a statistically significant difference (P less than 0.05). A significant correlation was found between the RT-HIS and density of beta-adrenergic receptors. From these results, we concluded that the exaggerated airway responsiveness 24 h after allergen challenge is in part due to a decrease in the density of beta-adrenergic receptors. There was no difference in the density of alpha-1-adrenergic receptors nor a significant correlation between the RT-HIS and the number of alpha-1-adrenergic receptors in the challenged vs. the control groups.     

The gamma T-cell antigen receptor

The gamma-TCR is encoded by genes composed of V, J, and C elements that demonstrate a limited potential for recombinational diversity. These genes are rearranged, transcribed, and translated into proteins early during thymic ontogeny. Lymphocytes express gamma-TCR proteins on the plasma membrane only in association with the CD3 complex. gamma-TCR glycoproteins usually associate with another non-gamma glycoprotein, designated delta-TCR, to form a heterodimer receptor. Both non-disulfide-bonded and disulfide-bonded gamma/delta-TCR heterodimers have been identified on the plasma membrane of human T lymphocytes. On certain gamma-TCR-bearing T cell lines, a delta-TCR protein cannot be visualized by autoradiography. It is possible that delta-TCR proteins are associated with gamma-TCR glycoproteins on these cell lines but are not efficiently radiolabeled. Alternatively, it has been suggested that homodimers of gamma-TCR proteins can assemble with CD3 and be expressed on the plasma membrane of these cells. In adult lymphoid tissues, the majority of T lymphocytes expresses a CD3, alpha/beta antigen receptor, whereas only a minor subset (less than 5% of peripheral blood lymphocytes, lymph node, spleen, and thymocytes) express a CD3, gamma/delta antigen receptor. IL-2-dependent cell lines of both murine and human CD3, gamma/delta T cells have been established. Most CD3, gamma/delta T cell lines mediate cytotoxicity against a broad spectrum of tumor-cell targets, although the functional significance of this observation remains unclear. Cytotoxicity is apparently not restricted by or directed against MHC antigens. Antibodies against CD3 or gamma-TCR can induce proliferation and IL-2 secretion and can either augment or inhibit cytotoxicity, demonstrating that the gamma/delta-TCR is a functional receptor. The ligand recognized by this receptor has not been identified. The physiological role of T lymphocytes expressing gamma/delta-TCR, the molecular and structural properties of delta-TCR, and the relationship between CD3, alpha/beta T lymphocytes and CD3, gamma/delta T lymphocytes are the major unresolved questions that will be the primary focus of further experimentation.     

T-cell receptor repertoire of circulating gamma delta T-cells in Takayasu's arteritis

We studied T-cell receptor (TCR) repertoire of circulating gamma delta (gammadelta) T-cells in 20 patients with Takayasu's arteritis (TA), 20 healthy controls (HC), 7 follow up TA patients, and 10 patients with rheumatoid arthritis (RA) and 5 Wegener's granulomatosis (WG) patients as disease controls. Patients with TA (8.1 +/- 5.1%) compared to HC (3.7 +/- 2.1%, P = 0.014), RA (4.8 +/- 0.6%, P = 0.032), and WG (4.2 +/- 0.8%, P = 0.030) as well as active TA compared to inactive TA (13.9 +/- 4.1% vs. 4.9 +/- 1.5%; P < 0.001) had higher number of gammadelta T-cells. The numbers of Vdelta1+ cells were significantly higher in patients with TA (40.0 +/- 20.8%) than HC (13.1 +/- 8.0%; P = 0.001), RA (19.5 +/- 1.8%, P = 0.004), and WG (17.0 +/- 3.9%, P = 0.007). The numbers of gammadelta T-cells normalized in all the 7 patients after 180 days of follow up (13.9 +/- 4.1% vs. 6.9 +/- 2.5%; P = 0.001). We also observed higher number of activated and IFN-gamma producing gammadelta T-cells in active TA. Our data show that gammadelta T-cells particularly those bearing Vdelta1 TCR may have an important role in the immunopathogenesis of TA.     

T-cell receptor β-chain DNA polymorphism frequencies in healthy HLA-DR homozygotes

In view of numerous recent reports of T-cell receptor (TCR) beta-chain/disease associations with HLA-associated diseases, we tested the possibilities that associations might exist directly between these two gene complexes at the level of the germline DNA. We determined frequencies of five TCR-beta DNA polymorphisms in 33 HLA-DR2/2 homozygotes, 29 HLA-DR3/3 homozygotes and 42 HLA-DR4/4 homozygotes. The control population (n = 74) was chosen without "bias toward" their HLA-DR genes. We selected DR2, DR3 and DR4 homozygotes because they have been the most frequently involved in HLA-DR associated diseases. Our results indicate that the recent reports in the literature of TCR-beta/disease associations can not be explained by a significantly different distribution of TCR-beta genes in HLA-DR2+, -DR3+, or -DR4+ subpopulations. Our results also suggest that if co-evolution between TCR-beta and MHC haplotypes does exist, the selective pressures in recent generations have not been strong enough to significantly alter the germline TCR-beta gene frequencies in HLA-DR2+, -DR3+, or -DR4+ subpopulations.