The gamma T-cell antigen receptor

Inhibition of methotrexate induced toxicity in the adult rat spleen by adalimumab

Methotrexate (MTX) has been in use for the treatment of rheumatoid arthritis (RA), psoriasis, and cancer since 1948. Its toxic side effects on tissues and organs have been well documented but splenotoxicity has not been addressed. This study set out to investigate this issue by examining the effectiveness of anti-TNFα agents against MTX-induced toxicity in T lymphocytes and macrophages via the regulation of CD3, CD68, and CD200R. Twenty-four Sprague Dawley rats were allocated to three groups: control (received saline solution only), MTX (20 mg/kg of single-dose of MTX), and Ada + MTX (single dose of 10 mg/kg Adalimumab before MTX administration). The spleens were removed 5 days after MTX administration. The number of CD3+/mm3cells for the control, MTX and Ada + MTX groups were, respectively, 2.69 ± 0.86, 20.51 ± 2.7, (p = 0.000) and 11.07 ± 2.01 (p = 0.000). The number of CD68+ macrophages/mm3 in the control, MTX and Ada + MTX groups were, respectively, 8.62 ± 1.08, 38.19 ± 1.37 (p = 0.000), and 16.87 ± 12.57 (p = 0.000). The number of macrophages that were CD200R+/mm3 in the control, MTX, and Ada + MTX groups were 3.33 ± 1.66, 25.77 ± 2.37 (p = 0.000), and 8.68 ± 2.66 (p = 0.000), respectively. We also observed that Ada reduced the numerical densities of these cells following MTX administration (p < 0.05). Ada may, therefore, be a promising candidate for the prevention of the deleterious effects on T lymphocytes and macrophages of MTX-induced toxicity.

IgG from Adult Atopic Dermatitis (AD) Patients Induces Nonatopic Neonatal Thymic Gamma-Delta T Cells (γδT) to Acquire IL-22/IL-17 Secretion Profile with Skin-Homing Properties and Epigenetic Implications Mediated by miRNA

γδT cells mature in the human thymus, and mainly produce IL-17A or IFN-γ, but can also produce IL-22 and modulate a variety of immune responses. Here, we aimed to evaluate whether IgG from AD patients (AD IgG) can functionally modulate thymic nonatopic γδT cells. Thymic tissues were obtained from 12 infants who had not had an atopic history. Thymocytes were cultured in mock condition, or in the presence of either AD IgG or therapeutic intravenous IgG (IVIg). Following these treatments, intracellular cytokine production, phenotype, and microRNA expression profiles were investigated. AD IgG could downregulate α4β7, upregulate CLA, and induce the production of IFN-γ, IL-17, and IL-22 in γδT cells. Although both AD IgG and IVIg could directly interact with γδT cell membranes, AD IgG could reduce γδT cell apoptosis. AD IgG could upregulate nine miRNAs compared to IVIg, and six when compared to the mock condition. In parallel, some miRNAs were downregulated. Target gene prediction and functional analysis indicated that some target genes were enriched in the negative regulation of cellular transcription. This study shows that AD IgG influences the production of IL-17 and IL-22 by intrathymic nonatopic γδT cells, and demonstrates epigenetic implications mediated by miRNAs.

IgG from Non-atopic Individuals Induces In Vitro IFN-γ and IL-10 Production by Human Intra-thymic γδT Cells: A Comparison with Atopic IgG and IVIg

Matured in the thymus, γδT cells can modulate the development of allergy in humans. The main γδT cell subsets have been described as interleukin (IL)-17A or interferon (IFN)-γ producers, but these cells can also produce other modulatory cytokines, such as IL-4 and IL-10. Here, we aimed to evaluate whether IgG can modulate the profile of cytokine production by γδT cells during their maturation in the thymus and after its migration to peripheral tissues. Thymic tissues were obtained from 12 infants, and peripheral blood mononuclear cells (PBMCs) were obtained from adults (both groups without an atopic background). IgG was purified from atopic and non-atopic volunteers. Thymocytes and PBMCs were cultured with purified atopic or non-atopic IgG, and intracellular cytokine production and phenotype were assessed. Mock and IVIg conditions were used as controls. IgG from non-atopic individuals induced IFN-γ and IL-10 production by thymic γδT cells, and no effect was observed on peripheral γδT cells. IL-17 production was inhibited by non-atopic IgG on thymic γδT cells and augmented by atopic IgG on peripheral γδT cells. Modulated thymic γδT cells did not produce IFN-γ and IL-10 simultaneously. We additionally evaluated the phenotype of intrathymic γδT cells and observed that IgG from all groups could induce CD25 expression and could not influence the CD28 expression of these cells. This report describes evidence revealing that IgG may influence the production of IFN-γ and IL-10 by intrathymic γδT cells depending on the donor atopic state. This observation is unprecedented and needs to be considered in further studies in the IgG immunotherapy field.

γδT Cells and Related Diseases

Discovered 30 years ago, γδT cells remain an enigmatic T-cell subset. Although they account for a small portion of the total human circulating T-cell pool, their associations with other immune cells and their potential regulatory roles in related diseases have been explored but still require further investigation. γδT cells which are MHC-unrestricted innate-like lymphocytes with more unique antigen receptors than αβT cells and B cells are considered to bridge innate and adaptive immunity. They have APC functions and initiate adaptive immunity. Due to their distribution in specific tissues, secretion of Th1-, Th2-, and Th17-type cytokines, and other characteristics, they are involved in a variety of physiology and pathology processes. They are barometers in HIV infection. However, different γδT cell subsets play opposing roles in HBV infections, autoimmune diseases, and several types of tumors. Moreover, decidual γδT cells have protective roles during pregnancies by synthesizing several cytokines. This emerging evidence provides an improved understanding of the immune mechanism of infection, autoimmunity, cancer, and other related disorders and better insights regarding the potential roles of γδT cells in immunological therapeutic strategies.

Expression of costimulatory molecules (CD80, CD86, CD28, CD152), accessory molecules (TCR αβ, TCR γδ) and T cell lineage molecules (CD4+, CD8+) in PBMC of leprosy patients using Mycobacterium leprae antigen (MLCWA) with murabutide and T cell peptide of Trat protein

In leprosy, cell-mediated immunity (CMI) is more significant than humoral response to eliminate intracellular pathogen. T cell defect is a common feature in lepromatous leprosy (LL) patients as compared to tuberculoid type (TT) patients. For efficient initiation of CD4+, T cell response requires T cell receptor (TCR) activation and costimulation provided by molecules on antigen-presenting cells (APC) and their counter receptors on T cells. In our previous study, the defective T cell function in LL patients was restored to a proliferating state with the release of TH1 type cytokines using mycobacterial antigen(s) with two immunomodulators (Murabutide (MDP-BE) and T cell epitope of Trat protein of Escherichia coli) by presenting the antigen in particulate form in vitro to PBMC derived from leprosy patients. This observation prompted us to study the expression of the costimulatory molecules (CD80, CD86, CD28, CD152), other accessory molecules (TCR alphabeta/gammadelta) and T cell lineage molecules (CD4+ and CD8+) during constitutive and activated state of peripheral blood mononuclear cells (PBMC) derived from normal and leprosy individuals using different formulations of Mycobacterium leprae total cell wall antigen (MLCWA), Trat and MDP-BE using flow cytometric analysis. An increased surface expression of CD80, CD86 and CD28 but decreased CD152 expression was observed when PBMC of normal, BT/TT (tuberculoid) and BL/LL (lepromatous) patients were stimulated in vitro with MLCWA+MDP-BE+Trat peptide using liposomal mode of antigen delivery, while opposite results were obtained with the antigen alone. Antibody inhibition study using antihuman CD80 or CD86 completely abolished the T cell lymphoproliferation, thereby reconfirming the importance of these costimulatory molecules during T cell activation/differentiation. Though the liposome-entrapped antigen formulation has no effect on expression of alphabeta/gammadelta T cell receptor, the constitutive levels of TCR gammadelta were high in lepromatous patients. Thus, TCR bearing gammadelta appears to have a negligible regulatory role in peripheral blood of leprosy patients. The percentage of cells positive for CD4+ are increased in inducible state in all the three groups, while CD8+-positive cells were decreased in LL patients, thereby reconfirming the fact that priming of CD4+ cells are necessary for producing final effector functions. Lastly, intracellular cytokine staining experiment indicated that CD4+ cells are the major producers of IFN-gamma but not NK cells. The study highlights the reversal of T cell anergy especially in lepromatous patients through the modulation of costimulatory molecule expression under the influence of Th1 cytokines, i.e., IL-2 and IFNgamma.

T-cell receptor gamma: a microsatellite marker for colorectal cancer

BACKGROUND

T-cell receptor gamma (TCR-gamma) is involved in maintaining host cell integrity and homeostasis of the human immune system. We hypothesize that polymorphism of the TCR-gamma complex may be involved in the pathogenesis of colorectal cancer.

METHODS

The microsatellite markers D7S1818 and D7S2206 located within the TCR-gamma antigen locus on chromosome 7p were amplified by polymerase chain reaction, and genotypes were determined for 22 patients with early onset of colorectal cancer (<60 years old) and for 38 population-based control subjects.

RESULTS

Genotype BC of D7S1818 (P = .049) and haplotype AC of D7S1818/D7S2206 (P < or = .003) were associated with colorectal cancer as compared with the control population (extended Fisher's exact test).

CONCLUSIONS

This study identifies a novel genetic and clinical association between TCR-gamma and early-onset colorectal cancer. Many young patients do not fulfill the criteria for hereditary colorectal cancer syndromes and are therefore not identified by established screening programs. Markers such as D7S1818 and D7S2206 may become useful in the identification of patients at risk of developing colorectal cancer and permit earlier therapeutic intervention.

gamma delta cells involved in contact sensitivity preferentially rearrange the Vgamma3 region and require interleukin-7

Ptak and Askenase showed that both alphabeta and gammadelta cells are required for transfer of contact sensitivity (CS). This study confirms that day 4 immune cells depleted of gammadelta cells fail to transfer CS to trinitrochlorobenzene (TNP-Cl) systemically and demonstrates that administration of anti-gammadelta monoclonal antibodies (mAb) in vivo abolishes the CS reaction. Moreover, gammadelta cells accumulate at the antigen challenge site: these cells have the unusual phenotype CD8alpha+, CD8beta-, IL-4 R+ which we suggest is due to their state of activation. Following immunization with contact sensitizer on the skin, the absolute number of gammadelta cells increases in the regional lymph nodes with a peak at 4 days. Of the gammadelta cells, 80 %, both in the lymph nodes of TNP-Cl-immune mice and accumulating at the antigen challenge site are Vgamma3+. The gammadelta cells expressing Vgamma3, which is characteristic of dendritic epithelial T cells (DETC), obtained 4 days after sensitization, proliferate in response to interleukin (IL)-7, but only poorly to IL-2 and IL-4. They also respond to concanavalin A and immobilized anti-gammadelta mAb, but not to haptens or heat-shocked syngeneic spleen cells. Furthermore, injection of mice with mAb to IL-7 inhibits accumulation of Vgamma3+ cells both in the lymph nodes after skin sensitization and at the antigen-challenge site. Altogether, these results strongly support the view that DETC are related to, or the original source of, the gammadelta cells found in the lymph node after skin sensitization and at the site of challenge, and that IL-7 is implicated in these phenomena.

Differential expression of heat shock proteins by human glial cells

Heat shock proteins (HSP) have been implicated in the interactions between the gamma delta T lymphocyte population and target tissues. gamma delta T cells are found in increased numbers in multiple sclerosis (MS) plaques compared to their proportion in peripheral blood, co-localizing with oligodendrocytes (OGC) expressing HSP. We have demonstrated that such gamma delta T cells can induce in vitro lysis of human adult-derived OGC. Using immunohistochemical and flow cytometry techniques, we examined the constitutive and/or inducible expression of HSP in or on adult human-derived glial cell cultures in vitro. HSP70 was expressed in OGC maintained at basal temperature, but the expression of the inducible HSP70 protein was upregulated by a prior 43 degrees C heat exposure. HSP70 could not be detected within astrocytes (GFAP+ cells), whether heat stress was applied or not. Constitutive expression of HSP60 could be discerned on the surface of all OGC under non-stressed culture conditions. Only some astrocytes demonstrated minor punctate surface HSP60 staining, whereas the remainder did not express HSP60 constitutively. These observations raise the possibility that OGC, by virtue of their differential expression of HSP compared to other glial cells, may be particularly prone to interaction with HSP-reactive gamma delta T cells. Such findings may further implicate gamma delta T cells in the pathogenesis of MS, a putative autoimmune disease in which immune-mediated injury is directed specifically against the oligodendrocyte-myelin unit within the central nervous system.

Fetal liver T cell receptor gamma/delta+ T cells as cytotoxic T lymphocytes specific for maternal alloantigens

We have established fetal liver-derived T cell receptor (TCR) gamma/delta+, CD3+ T cell lines that are cytotoxic for maternal T cells. Fetal liver-derived lymphoid progenitors yielded predominantly TCR-gamma/delta+ cell clusters when cultured on fetal bone marrow-derived stromal cells in the presence of a cytokine cocktail under magnetic force. These tightly adherent clusters were cloned by limiting dilution and the resulting cell lines analyzed for phenotype and function. Six of eight TCR-gamma/delta lines from 8-9.5-wk gestation fetuses were V delta 2+ as compared with zero of eight lines from later stages of gestation (10 and 15 wk), where all the lines were V delta 1+. In cytotoxicity assays, these TCR-gamma/delta+, CD3+, CD4-, and CD8+ or CD8- long-term cultured lymphoid cells (LLC) were killer cells active against the class I antigens on maternal T cells. Of the cell lines, the CD8+ TCR-gamma/delta+ LLC had the highest levels of killer activity. Thus fetal liver TCR-gamma/delta+ T cells may play a crucial role in protection against invading maternal T cells generated in the feto-maternal interaction.

Phenotype, activation and lymphokine secretion by gamma/delta T lymphocytes from schistosomiasis and carcinoma of the urinary bladder

In humans the majority of the CD3+ T cells usually express an alpha/beta T cell receptor (TcR) and a minority express a gamma/delta TcR. The CD3+ TcR alpha/beta and CD3+ TcR gamma/delta cells from blood of the patients with schistosomiasis with carcinoma of the urinary bladder (SCB) were analyzed for phenotype, activation, secretion of interleukin 2 (IL 2). B cell growth factor (BCGF) and B cell differentiation factor (BCDF), as well as for autologous (AMLR) and allogeneic (MLR) mixed lymphocyte reaction. Patients with SCB had a highly increased percentage of CD3+ TcR gamma/delta and a decreased percentage of CD3+ TcR alpha/beta T cells in their circulation. These CD3+ TcR gamma/delta T cells expressed the CD25 (IL 2 receptor), CD38, CD71 (transferrin receptor) and HLA-DR activation antigens at a higher intensity after in vitro stimulation with recombinant IL 2, phytohemagglutinin and soluble egg antigen (from Schistosoma haematobium). The SCB patients' CD3+ TcR gamma/delta T cells were highly deficient in secretion of IL 2 but produced highly elevated levels of BCGF and BCDF. On the contrary, both BCGF and BCDF activities of the CD3+ TcR alpha/beta T cells were decreased. Moreover, CD3+ TcR gamma/delta T cells demonstrated highly deficient AMLR and MLR activity. These observations suggest a possible role of CD3+ TcR gamma/delta T cells in the immune response and the disease pathogenesis in human schistosomiasis infections.

A subset of gamma delta lymphocytes is increased during HIV-1 infection

The gamma delta T cell receptor (TcR) lymphocytes constitute 3-10% of human peripheral blood lymphocytes. Only a very small fraction of these cells is recognized by the delta TCS1 monoclonal antibody, directed against the V delta 1 chain of the receptor. We describe the immunological, virological and clinical data of a small group of seropositive subjects having high levels of gamma delta TcR T cells in the peripheral blood. Our flow cytometric studies show that most of these cells belong to the delta TCS1+ (V delta 1+), CD8 +/- (dim staining) subset. Patients with high gamma delta TcR T cell numbers were not characterized by the presence of an acute (IgM positive) or reactivated (as defined by high IgG titres against early antigen or IgA titres against viral capsidic antigen) Epstein-Barr virus infection. Cytomegalovirus infection was excluded by serological assays, and other herpes viral infections were not found after clinical examination. HIV p24 antigenaemia was present in two out of 11 subjects. AIDS patients had very high percentages of gamma delta TcR T cells. Altogether these data show that the selective expansion of delta TCS1+ cells in HIV1 seropositive subjects is not related to some exogenous antigen stimulation, but may be related to peculiar pathologic processes involving the immune system.

gamma delta T-cell receptor-positive T-cell clones derived from human heart transplants do not show donor-specific cytotoxicity

gamma delta T-cell receptor-positive T-cell clones were obtained from three endomyocardial biopsies taken from two patients. Clones obtained from two biopsies from patient A, one taken during rejection and one after resolution of this rejection, were WT31-, 11F2+, Ti gamma A-, delta TcS1+. Clones from patient B grown from a biopsy without histologic signs of rejection were either WT31-, 11F2+, Ti gamma A+, delta TcS1-, or WT31+. All gamma delta T-cell receptor-positive clones had cytolytic potential but did not demonstrate donor-specific lysis.

Immunological studies in tropical spastic paraparesis

Tropical spastic paraparesis (TSP) and other chronic-progressive myelopathies have been clearly associated with increased serum and cerebrospinal fluid antibody titers to human T-lymphotropic virus type I (HTLV-I). However, little is known about the cellular immune function in TSP. In the present study, activated T lymphocytes were found in the peripheral blood of patients with TSP. Specifically, there were increased numbers of large CD3+ cells that also expressed HLA-DR and interleukin-2-receptor molecules. A significantly elevated spontaneous lymphoproliferative response was demonstrated in all patients tested. Generation of measles virus-specific cytotoxic T-cell response was reduced in 4 of 4 patients. This was similar to previous findings in patients with multiple sclerosis. However, unlike multiple sclerosis, reduced generation of cytotoxic T-cell response to influenza and mumps viruses was observed in 2 of 4 patients. These observations confirm further the strong association between TSP and an HTLV-I-like virus and suggest that the observed abnormalities of the cellular immune response in TSP are related to infection of lymphocytes by the retrovirus.

Phenotypic analysis of a CD2- CD3+ T cell receptor gamma delta lymphocyte subset

We have identified, in a patient with atopic dermatitis, a consistent population of peripheral blood lymphocytes expressing a CD3+ gamma/delta TCR complex, while being unreactive with CD2. Further immunofluorescence studies showed that these cells almost completely co-express CD29 and CD45RA and have high membrane levels of CD11a compared to the alpha/beta TCR T cells. Neither a genetic influence nor an acute or reactivated herpesvirus infection were found to be related to the expanded gamma/delta T-cell subpopulation. Our data confirm the previous observations regarding the presence in the peripheral blood of an expanded gamma/delta TCR, CD2- subset and show that these cells have a peculiar phenotypic profile. The reasons for this expansion are, however, still unknown.

Structural and serological heterogeneity of gamma/delta T cell antigen receptor expression in thymus and peripheral blood

Monoclonal antibodies (mAb) reactive against the gamma/delta T cell antigen receptor (TcR) have been used to characterize the distribution and structural properties of gamma/delta TcR-bearing lymphocytes in blood and thymus. Consistent with prior reports the TcR gamma/delta-1 and delta-1 mAb react with all gamma/delta TcR+ T lymphocytes in blood and thymus. By contrast the TCS-delta mAb was found only to react with a subset of the gamma/delta TcR-bearing T cell population. Several lines of evidence suggest that this reagent preferentially reacts with the V delta 1 gene product. Using these reagents, it was observed that gamma/delta TcR+ T lymphocytes comprise 4.6 +/- 3.5% (range 1.0-16.3%) of peripheral blood lymphocytes. However, analysis of peripheral blood from normal adult donors revealed that in 29 of 32 the TCS-delta (possibly V delta 1)-bearing cells comprised less than 30% of the total gamma/delta-TcR+ population. Biochemical analysis demonstrated that the predominant form of the gamma/delta TcR in adult peripheral blood is a disulfide-linked heterodimer, indicating preferential use of the C gamma 1 gene. The delta TcR chain from these TcR-gamma/delta-1+/TCS-delta- T cells was remarkably basic in charge, as analyzed by nonequilibrium pH gradient electrophoresis. By contrast with peripheral blood the majority of freshly isolated and interleukin 2-cultured gamma/delta TcR+ thymocytes were predominantly TcR-gamma/delta-1+/TCS-delta +, and preferentially expressed V delta 1. Moreover, both disulfide-bonded and nondisulfide-bonded gamma/delta TcR heterodimers were expressed in all thymuses examined and both forms were contained within the TCS-delta + thymic subset. Similar to recent findings in the mouse, these studies suggest a possible bias in the structural form of gamma/delta TcR based on tissue location.

The lysine residue in the membrane-spanning domain of the beta chain is necessary for cell surface expression of the T cell antigen receptor

The TCR is a complex receptor composed of seven polypeptide chains consisting of a ligand-binding subunit, Ti, and a putative signal-transducing subunit, CD3. Phylogenetically conserved charged amino acid residues within the membrane-spanning domains present in all seven chains of the TCR have been proposed to be important in the association between Ti and CD3. Using a Ti beta chain-deficient mutant of the cell line Jurkat, site-directed mutagenesis and transfection of Ti beta chain cDNA was performed to assess the importance of the lysine residue at position 290 within the membrane-spanning domain of the Ti beta chain to expression of the TCR complex. These studies demonstrated that the lysine residue, and not simply conservation of either basic charge or secondary structure, is important at this position.

Phenotypic heterogeneity and cytotoxic activity of Con A and IL-2-stimulated cultures of mouse Thy-1+ epidermal cells

Short-term and long-term cultures of mouse Thy-1+ epidermal cells (EC) were established in order to characterize their phenotypic and functional properties. Concanavalin A (Con A) and Interleukin 2 (IL-2) stimulated Thy-1+ EC mediated non-MHC directed cytotoxicity preferentially against the NK-sensitive target, YAC-1 vs the NK-resistant target, P815; these cells also mediated antibody-dependent cell-mediated cytotoxicity (ADCC), indicating the presence of IgG-FcR on at least some of them. Freshly isolated Thy-1+ EC failed to lyse YAC-1 targets; however, this activity was observed after 9 d of culture with Con A and IL-2. While dendritic Thy-1+ EC, in vivo, do not express the T-cell markers, L3T4 and Lyt-2, short-term cultured cells displayed phenotypic heterogeneity with small but significant percentages of Lyt-2+ and L3T4+ cells appearing transiently. The phenotype of the effector cell(s), which mediates cytotoxic activity, was determined by utilizing flow cytometry to sort short-term cultured EC into positively and negatively stained populations. Cells which express L3T4, or which lack asialo GM1, did not lyse YAC-1 targets; maximum cytotoxic activity was found within populations of cells which are asialo GM1+, Lyt-2-, and asialo GM1+, Lyt-2+. These studies indicate that Thy-1+ cells derived from mouse epidermis when cultured in the presence of Con A and IL-2 have the capacity to generate a phenotypically heterogeneous population, some cells of which are capable of mediating cytotoxic activities.