Immunological Characteristics between αß TDC and γδ TDC Cells in the Spleen of Breast Cancer-Induced Mice.

OBJECTIVE: To evaluate the antitumoral role of γδ TDC cells and αß TDC cells in an experimental model of breast cancer. METHODS: Thirty female Balb/c mice were divided into 2 groups: control group (n = 15) and induced-4T1 group (n = 15), in which the mice received 2 × 105 4T1 mammary tumor cell line. Following the 28-day experimental period, immune cells were collected from the spleen and analyzed by flow cytometry for comparison of αß TDC (TCRαß+ CD11c+MHCII+) and γδ TDC (TCRγδ+CD11c+MHCII+) cells regarding surface markers (CD4+ and C8+) and cytokines (IFN-γ, TNF-α, IL-12 and IL-17). RESULTS: A total of 26.53% of γδ TDC - control group (p < 0.0001) - the proportion of αß TDC was lower in splenic cells than γδ TDC; however, these 2 cell types were reduced in tumor conditions (p < 0.0001), and the proportion of IFN-γ, TNF-α, IL-12 and IL-17 cytokines produced by γδ TDC was higher than those produced by αß TDC, but it decreased under conditions of tumor-related immune system response (p < 0.0001). CONCLUSION: Healthy mice engrafted with malignant cells 4T1 breast tumor presented TDC with γδ TCR repertoire. These cells express cytotoxic molecules of lymphocytes T, producing anti-tumor proinflammatory cytokines.

OBJETIVO: Esclarecer o possível papel antitumoral das células TDC γδ e TDC αß em um modelo experimental de câncer de mama. MéTODOS: Trinta baços de camundongos Balb/c analisados por citometria de fluxo, separados entre grupo controle (n = 15) e o grupo tumoral induzido por 4T1 (n = 15). RESULTADOS: Presença de 26,53% de TDC γδ nos camundongos do grupo controle (p < 0,0001), proporção de TDC αß menor em células esplênicas do que TDC γδ; no entanto, estes dois tipos de células são reduzidos em condições tumorais (p < 0,0001), e a proporção de citocinas IFN-γ, TNF-α, IL-12 e IL-17 produzidas pelas célula TDC γδ foi maior do que as produzidas pelas células TDC αß, mas foram diminuídas sob condições de resposta ao sistema imunológico relacionada ao tumor (p < 0,0001). CONCLUSãO: Camundongos saudáveis induzidos ao tumor de mama 4T1 apresentaram TDC com repertório TCR γδ. Estas células expressam moléculas citotóxicas de linfócitos T, produzindo citocinas proinflamatórias anti-tumor.

Immunological Characteristics between αß TDC and γδ TDC Cells in the Spleen of Breast Cancer-Induced Mice / Características imunológicas entre células TDC αß e TDC γδ no baço de camundongos com câncer de mama induzido

Abstract Objective To evaluate the antitumoral role of γδ TDC cells and αβ TDC cells in an experimental model of breast cancer. Methods Thirty female Balb/c mice were divided into 2 groups: control group (n=15) and induced-4T1 group (n=15), in which the mice received 2 x 105 4T1 mammary tumor cell line. Following the 28-day experimental period, immune cells were collected from the spleen and analyzed by flow cytometry for comparison of αβ TDC (TCRαβ+ CD11c+MHCII+) and γδ TDC (TCRγδ+CD11c+MHCII+) cells regarding surface markers (CD4+ and C8+) and cytokines (IFN-γ, TNF-α, IL-12 and IL-17). Results A total of 26.53% of γδ TDC- control group (p<0.0001) - the proportion of αβ TDC was lower in splenic cells than γδ TDC; however, these 2 cell types were reduced in tumor conditions (p<0.0001), and the proportion of IFN-γ, TNF-α, IL-12 and IL-17 cytokines produced by γδ TDC was higher than those produced by αβ TDC, but it decreased under conditions of tumor-related immune system response (p<0.0001). Conclusion Healthy mice engrafted with malignant cells 4T1 breast tumor presented TDC with γδ TCR repertoire. These cells express cytotoxic molecules of lymphocytes T, producing anti-tumor proinflammatory cytokines.

Resumo Objetivo Esclarecer o possível papel antitumoral das células TDC γδ e TDC αβ em um modelo experimental de câncer de mama. Métodos Trinta baços de camundongos Balb/c analisados por citometria de fluxo, separados entre grupo controle (n=15) e o grupo tumoral induzido por 4T1 (n=15). Resultados Presença de 26,53% de TDC γδ nos camundongos do grupo controle (p<0,0001), proporção de TDC αβ menor em células esplênicas do que TDC γδ; no entanto, estes dois tipos de células são reduzidos emcondições tumorais (p<0,0001), e a proporção de citocinas IFN-γ, TNF-α, IL-12 e IL-17 produzidas pelas célula TDC γδ foi maior do que as produzidas pelas células TDC αβ, mas foram diminuídas sob condições de resposta ao sistema imunológico relacionada ao tumor (p<0,0001). Conclusão Camundongos saudáveis induzidos ao tumor de mama 4T1 apresentaram TDC com repertório TCR γδ. Estas células expressam moléculas citotóxicas de linfócitos T, produzindo citocinas proinflamatórias anti-tumor.

Immunization With the CSF-470 Vaccine Plus BCG and rhGM-CSF Induced in a Cutaneous Melanoma Patient a TCRß Repertoire Found at Vaccination Site and Tumor Infiltrating Lymphocytes That Persisted in Blood.

The CSF-470 cellular vaccine plus BCG and rhGM-CSF increased distant metastases-free survival in cutaneous melanoma patients stages IIB-IIC-III relative to medium dose IFN-α2b (CASVAC-0401 study). Patient-045 developed a mature vaccination site (VAC-SITE) and a regional cutaneous metastasis (C-MTS), which were excised during the protocol, remaining disease-free 36 months from vaccination start. CDR3-TCRß repertoire sequencing in PBMC and tissue samples, along with skin-DTH score and IFN-γ ELISPOT assay, were performed to analyze the T-cell immune response dynamics throughout the immunization protocol. Histopathological analysis of the VAC-SITE revealed a highly-inflamed granulomatous structure encircled by CD11c+ nested-clusters, brisk CD8+ and scarce FOXP3+, lymphocytes with numerous Langhans multinucleated-giant-cells and macrophages. A large tumor-regression area fulfilled the C-MTS with brisk lymphocyte infiltration, mainly composed of CD8+PD1+ T-cells, CD20+ B-cells, and scarce FOXP3+ cells. Increasing DTH score and IFN-γ ELISPOT assay signal against the CSF-470 vaccine-lysate was evidenced throughout immunization. TCRß repertoire analysis revealed for the first time the presence of common clonotypes between a VAC-SITE and a C-MTS; most of them persisted in blood by the end of the immunization protocol. In vitro boost with vaccine-lysate revealed the expansion of persistent clones that infiltrated the VAC-SITE and/or the C-MTS; other persistent clones expanded in the patient's blood as well. We propose that expansion of such persistent clonotypes might derive from two different although complementary mechanisms: the proliferation of specific clones as well as the expansion of redundant clones, which increased the number of nucleotide rearrangements per clonotype, suggesting a functional antigenic selection. In this patient, immunization with the CSF-470 vaccine plus BCG and rhGM-CSF induced a T-cell repertoire at the VAC-SITE that was able to infiltrate an emerging C-MTS, which resulted in the expansion of a T-cell repertoire that persisted in blood by the end of the 2-year treatment.

Preservation of cytotoxic granule production in response to mycobacterial antigens by T-lymphocytes from vertically HIV-infected Brazilian youth on effective combined antiretroviral therapy.

BACKGROUND: HIV infection harms adaptive cellular immunity mechanisms. Long-term virological control by combined antiretroviral therapy (cART) reduces the risk of mycobacterial infections. Thus, we aimed to study cellular responses to mycobacterial antigens in 20 HIV-infected adolescents with at least one year of virological control (HIV-RNA <40 copies/mL) and 20 healthy adolescents. METHODS: We evaluated CD8 and γδ T-cell degranulation by measurement of CD107a membrane expression after stimulation with lysates from BCG (10 µg/mL) and H37RA Mycobacterium tuberculosis (Mtb, 10 µg/mL). Immune activation and antigen-presenting ability were also assessed by determination of HLA-DR, CD80, and CD86 markers. RESULTS: TCR γδ T-cell CD107a expression was similar between groups in response to mycobacterial antigens, and lower in the HIV-infected group in response to mitogen. Higher baseline HLA-DR expression and lower mycobacterial-stimulated expression was found within the HIV-infected group. CONCLUSIONS: Similar degranulation in stimulated CD8+ and TCR γδ T-cells from HIV-infected adolescents, when compared to healthy controls suggests long-term immunological preservation with immune reconstitution under successful cART. However, differences in HLA-DR expression may represent ongoing inflammation and lower specific responses in HIV-infected youth. These features may be relevant in the context of the precocity and severity of vertically acquired HIV infection.

Preservation of cytotoxic granule production in response to mycobacterial antigens by T-lymphocytes from vertically HIV-infected Brazilian youth on effective combined antiretroviral therapy

ABSTRACT Background: HIV infection harms adaptive cellular immunity mechanisms. Long-term virological control by combined antiretroviral therapy (cART) reduces the risk of mycobacterial infections. Thus, we aimed to study cellular responses to mycobacterial antigens in 20 HIV-infected adolescents with at least one year of virological control (HIV-RNA <40 copies/mL) and 20 healthy adolescents. Methods: We evaluated CD8 and γδ T-cell degranulation by measurement of CD107a membrane expression after stimulation with lysates from BCG (10 µg/mL) and H37RA Mycobacterium tuberculosis (Mtb, 10 µg/mL). Immune activation and antigen-presenting ability were also assessed by determination of HLA-DR, CD80, and CD86 markers. Results: TCR γδ T-cell CD107a expression was similar between groups in response to mycobacterial antigens, and lower in the HIV-infected group in response to mitogen. Higher baseline HLA-DR expression and lower mycobacterial-stimulated expression was found within the HIV-infected group. Conclusions: Similar degranulation in stimulated CD8+ and TCR γδ T-cells from HIV-infected adolescents, when compared to healthy controls suggests long-term immunological preservation with immune reconstitution under successful cART. However, differences in HLA-DR expression may represent ongoing inflammation and lower specific responses in HIV-infected youth. These features may be relevant in the context of the precocity and severity of vertically acquired HIV infection.

TCR Vß Usage of Peripheral Blood and Liver Infiltrating Lymphocytes in Patients with Chronic Hepatitis B.

INTRODUCTION: Chronic hepatitis B (CHB) is still a public health problem and its mechanism remains unclear. In this study, we detect the skewness of T cell receptor beta chain variable gene (TCR Vß) in peripheral blood lymphocytes (PBL) and the liver infiltrating lymphocytes (LIL) of patients with CHB; and hope to provide information for further research on the pathogenic mechanism of CHB. MATERIAL AND METHODS: Fifteen patients with CHB, ten healthy volunteers and three patients with liver cysts were recruited as the subjects. The usage of TCR Vß of PBL and LIL were measured and compared; the associations of the TCR Vß usage of PBL with some hematological indices, including human leukocyte antigen (HLA) alleles, percents of CD4+ and CD8+ T cells, sera levels of HBV-DNA and IFN-γ, were analyzed. RESULTS: In PBL, Vß12 and Vß13.1 were the highest predominant usage genes which usage frequencies were all 46.7%; Vß23 was the key limited usage gene (40.0%). In LIL, the mainly predominant and limited usage gene was Vß13.1 (73.3%) and Vß23 (46.7%), respectively. About half of the patients with CHB with HLA-DR9 or HLA-DR12 showed the predominant usage of Vß5.2 or Vß13.2. In patients with CHB, the percentage of CD4+ T cells was 33.41 ± 5.39 %, that of CD8+ T cells was 28.67 ± 6.77 %; the concentration of IFN-γ was 182.52 ± 44.16 pg/mL. Compared to the healthy controls, there were significant differences for these data (P < 0.05). Neither ALT nor HBV-DNA was relative to the usage of TCR Vß. CONCLUSIONS: PBL and LIL share the common sknewness of TCR Vß genes, which probably relates to some hematological indices. However, the roles of such similarities and associations in the development of CHB need further study.

MAIT-cells: A tailor-made mate in the ancient battle against infectious diseases?

It has been almost two decades since the discovery of mucosal-associated invariant T (MAIT)-cells. Several advances in the field have been made such as the discovery of the antimicrobial activity of MAIT-cells, the abundance of these cells in human mucosa and in liver and the discovery of ligands able to bind MR1 and activate MAIT-cells. MAIT-cells are a unique subset of innate-like T-cells that express a canonical T-cell receptor with the alpha chain containing hAV7S2 and AJ33 in humans (TCRVα7.2Jα33) and respond to bacterial/fungus vitamin B2 metabolites by an MR1-dependent pathway. Indirect activation is also observed during chronic viral infections by and IL-12/IL-18 pathway. In this review, the mechanisms of activation, the timeline of MAIT-cell development in humans as well as their role in human infection are discussed. On the whole, we believe that harnessing the anti-microbial ability of MAIT-cells could contribute for the design of potent immunotherapies and vaccines against "hard-to-kill" infectious agents that remain as public health threats worldwide.

High-Throughput Sequencing Reveals Immunological Characteristics of the TRB-/IgH-CDR3 Region of Umbilical Cord Blood.

OBJECTIVE: To compare the differences of immunological characteristics between newborn and adults, we performed high-throughput sequencing to reveal the diversity of umbilical cord blood and adult peripheral blood at both T-cell receptor beta chain (TRB) and immunoglobulin heavy chain (IGH) levels. STUDY DESIGN: High-throughput sequencing was performed to analyze the expression of TRB-CDR3 and IGH-CDR3 in circulating T and B cells isolated from 20 healthy adults, 56 pregnant women, and 40 newborns. RESULTS: Our results revealed different immunological characteristics between newborn and adults, such as distinctive complementarity determining region 3 (CDR3) lengths, usage bias of variable and joining segments, random nucleotide addition, a large number of unique CDR3 peptides, and a greater repertoire diversity. Moreover, each newborn had a distinctive TRB-/IGH-CDR3 repertoire that was independent of the maternal immune status. CONCLUSIONS: This study presents comprehensive, unrestricted profiles of the TRB/IGH-CDR3 repertoire of newborns, pregnant women, and healthy adults at a sequence-level resolution. Our data may contribute to a better understanding of the immune system of newborns and benefit the efficient application of umbilical cord blood transplantation in future.

Epstein-Barr virus-specific CD8(+) T lymphocytes from diffuse large B cell lymphoma patients are functionally impaired.

Epstein-Barr virus (EBV) is a persistent virus with oncogenic capacity that has been implicated in the development of aggressive B cell lymphomas, primarily in immunosuppressed individuals, although it can be present in immunocompetent individuals. Changes in the function and clonal diversity of T lymphocytes might be implied by viral persistence and lymphoma development. The aim of the present study was to evaluate the frequency, phenotype, function and clonotypical distribution of EBV-specific T cells after peripheral blood stimulation with a virus lysate in newly diagnosed patients with diffuse large B cell lymphoma (DLBCL) aged more than 50 years without prior histories of clinical immunosuppression compared with healthy controls. Our results showed impaired EBV-specific immune responses among DLBCL patients that were associated primarily with decreased numbers of central and effector memory CD8(+) T lymphocytes. In contrast to healthy controls, only a minority of the patients showed CD4(+)/tumour necrosis factor (TNF)-α(+) T cells expressing T cell receptor (TCR)-Vß17 and CD8(+)/TNF-α(+) T cells with TCR-Vß5·2, Vß9 and Vß18 in response to EBV. Notably, the production of TNF-α was undetectable among TCR-Vß5·3(+), Vß11(+), Vß12(+), Vß16(+) and Vß23(+) CD8(+) T cells. In addition, we observed decreased numbers of CD4(+)/TNF-α(+) and CD8(+)/TNF-α(+), CD8(+)/interleukin (IL)-2(+) and CD8(+)/TNF-α(+)/IL-2(+) T lymphocytes in the absence of T cells capable of producing TNF-α, IL-2 and IFN-γ after EBV stimulation simultaneously. Moreover, DLBCL patients displayed higher IL-10 levels both under baseline conditions and after EBV stimulation. These findings were also observed in patients with positive EBV viral loads. Prospective studies including a large number of patients are needed to confirm these findings.

Phage display of functional αß single-chain T-cell receptor molecules specific for CD1b:Ac2SGL complexes from Mycobacterium tuberculosis-infected cells.

The development of molecules specific for M. tuberculosis-infected cells has important implications, as these tools may facilitate understanding of the mechanisms regulating host pathogen interactions in vivo. In addition, development of new tools capable to targeting M. tuberculosis-infected cells may have potential applications to diagnosis, treatment, and prevention of tuberculosis (TB). Due to the lack of CD1b polymorphism, M. tuberculosis lipid-CD1b complexes could be considered as universal tuberculosis infection markers. The aim of the present study was to display on the PIII surface protein of m13 phage, a human αß single-chain T-cell receptor molecule specific for CD1b:2-stearoyl-3-hydroxyphthioceranoyl-2´-sulfate-α-α´-D-trehalose (Ac2SGL) which is a complex presented by human cells infected with M. tuberculosis. The results showed the pIII fusion particle was successfully displayed on the phage surface. The study of the recognition of the recombinant phage in ELISA and immunohistochemistry showed the recognition of CD1b:Ac2SGL complexes and cells in human lung tissue from a tuberculosis patient respectively, suggesting the specific recognition of the lipid-CD1b complex.

TLR7 triggering with polyuridylic acid promotes cross-presentation in CD8α+ conventional dendritic cells by enhancing antigen preservation and MHC class I antigen permanence on the dendritic cell surface.

ssRNA can interact with dendritic cells (DCs) through binding to TLR7, inducing secretion of proinflammatory cytokines and type I IFN. Triggering TLR7 enhances cross-priming of CD8(+) T cells, which requires cross-presentation of exogenous Ag to DCs. However, how TLR triggering can affect Ag cross-presentation is still not clear. Using OVA as an Ag model, we observed that stimulation of TLR7 in DCs by polyuridylic acid (polyU), a synthetic ssRNA analog, generates a strong specific cytotoxic response in C57BL/6 mice. PolyU stimulate CD8α(+) DCs to cross-prime naive CD8(+) T cells in a type I IFN-dependent fashion. This enhanced cross-priming is accompanied by a higher density of OVA(256-264)/H-2K(b) complexes on CD8α(+) DCs treated with polyU, as well as by upregulation of costimulatory molecules and increased secretion of proinflammatory cytokines by DCs. Cross-priming of CD8(+) T cells by DCs treated with polyU requires proteasome and Ag translocation to cytosol through the Sec61 channel in DCs. The observed enhancement in OVA cross-presentation with polyU in DCs could be mediated by a limited Ag degradation in endophagosomal compartments and a higher permanence of OVA peptide/MHC class I complexes on DCs. These observations clearly reveal that key steps of Ag processing for cross-presentation can be modulated by TLR ligands, opening new avenues for understanding their mechanisms as adjuvants of the immune response.

CD4-CD8-αß and γδ T cells display inflammatory and regulatory potentials during human tuberculosis.

T-cells play an important role controlling immunity against pathogens and therefore influence the outcome of human diseases. Although most T-lymphocytes co-express either CD4 or CD8, a smaller T-cell subset found the in the human peripheral blood that expresses the αß or γδ T-cell-receptor (TCR) lacks the CD4 and CD8 co-receptors. These double negative (DN) T-cells have been shown to display important immunological functions in human diseases. To better understand the role of DN T-cells in human Mycobacterium tuberculosis, we have characterized their frequency, activation and cytokine profile in a well-defined group of tuberculosis patients, categorized as severe and non-severe based on their clinical status. Our data showed that whereas high frequency of αß DN T-cells observed in M. tuberculosis-infected patients are associated with disease severity, decreased proportion of γδ DN T-cells are found in patients with severe tuberculosis. Together with activation of CD4(+) and CD8(+) T-cells, higher frequencies of both αß and γδ DN T-cells from tuberculosis patients also express the chronic activation marker HLA-DR. However, the expression of CD69, an early activation marker, is selectively observed in DN T-cells. Interestingly, while αß and γδ DN T-cells from patients with non-severe tuberculosis display a pro-inflammatory cytokine profile, characterized by enhanced IFN-γ, the γδ DN T-cells from patients with severe disease express a modulatory profile exemplified by enhanced interleukin-10 production. Overall, our findings suggest that αß and γδ DN T-cell present disparate immunoregulatory potentials and seems to contribute to the development/maintenance of distinct clinical aspects of TB, as part of the complex immunological network triggered by the TB infection.

Highly conserved CDR3 region in circulating CD4(+)Vß5(+) T cells may be associated with cytotoxic activity in Chagas disease.

Human infection with Trypanosoma cruzi leads to Chagas disease, which presents as several different clinical conditions ranging from an asymptomatic form to a severe dilated cardiomyopathy. Several studies have demonstrated that T cells play a critical role in the development of cardiac pathology, as well as in immunoregulation during chronic disease. However, the mechanisms that drive protective or pathogenic T cell response are not known. We have shown that CD4(+) T cells from chagasic patients preferentially express T cell receptor (TCR) ß-chain variable region (Vß) 5. The aim of this work was to determine whether T cells expressing this particular Vß region displayed variable or restricted CDR3 sequences, as an indicator of the nature of the stimulus leading to the activation of these T cells in vivo. Additionally, we aimed to evaluate phenotypic characteristics of these cells that might be associated with pathology. CDR3 junctional region sequencing of Vß5·1 expressing CD4(+) T cells revealed the occurrence of a highly homologous CDR3 region with conserved TCR Jß region usage among patients with cardiac, but not indeterminate, Chagas disease. Moreover, correlation analysis indicated that the frequency of CD4(+)Vß5·1(+) cells is associated with granzyme A expression, suggesting that these cells might display cytotoxic function. Together these results provide new insight into T cell recognition of antigens involved in Chagas disease and suggest that these cells may be implicated in the pathogenesis of chagasic cardiomyopathy.

Trypanosoma cruzi-induced activation of functionally distinct αß and γδ CD4- CD8- T cells in individuals with polar forms of Chagas' disease.

CD4(-) CD8(-) (double-negative [DN]) T cells have recently been shown to display important immunological functions in human diseases. They express γδ or αß T-cell receptors that recognize lipid/glycolipid antigens presented via the nonclassical major histocompatibility complex molecules of the CD1 family. We recently demonstrated that while αß DN T cells serve primarily to express inflammatory cytokines, γδ DN T cells express mainly interleukin-10 (IL-10) in patients with cutaneous leishmaniasis. We also demonstrated a correlation between DN T cells and the expression of gamma interferon in the acute phase of Trypanosoma cruzi experimental infection. In this work, we sought to investigate whether αß or γδ DN T cells display distinct immunoregulatory potentials in patients with polar forms of human Chagas' disease. Our data showed that in vitro infection with T. cruzi leads to expansion of DN T cells in patients with the indeterminate and severe cardiac clinical forms of the disease. However, while αß DN T cells primarily produce inflammatory cytokines in both forms of the disease, γδ DN T cells display a marked, significant increase in antigen-specific IL-10 expression in indeterminate patients relative to cardiac patients. Finally, higher frequencies of the IL-10-producing γδ DN T cells were correlated with improved clinical measures of cardiac function in the patients, suggesting a protective role for these cells in Chagas' disease. Taken together, these data show distinct functional characteristics for αß and γδ DN T cells associated with distinct morbidity rates and clinical forms in human Chagas' disease.

T cell receptor beta chain (TCR-Vbeta) repertoire of circulating CD4(+) CD25(-), CD4(+) CD25(low) and CD4(+) CD25(high) T cells in patients with long-term renal allograft survival.

The mechanisms underlying maintenance of renal allografts in humans under minimal or conventional immunosuppression are poorly understood. There is evidence that CD4(+) CD25(+) regulatory T cells and clonal deletion, among other mechanisms of tolerance, could play a key role in clinical allograft survival. Twenty-four TCR-Vbeta families were assessed in CD4(+) CD25(-), CD4(+) CD25(low) and CD4(+) CD25(high) T cells from patients with long-term renal allograft survival (LTS), patients exhibiting chronic rejection (ChrRx), patients on dialysis (Dial) and healthy controls (HC) by flow cytometry. LTS patients presented a higher variability in their TCR-Vbeta repertoire, such decreased percentage of Vbeta2(+), Vbeta8a(+) and Vbeta13(+) in CD4(+) CD25(low) and (high) compared with CD4(+) CD25(-) subset and increased Vbeta4 and Vbeta7 families in CD4(+) CD25(high) T cells exclusively. Additionally, LTS patients, particularly those that were not receiving calcineurin inhibitors (CNI), had increased percentages of CD4(+) CD25(high) T cells when compared with Dial (P < 0.05) and ChrRx (P < 0.05) patients. Our results suggest that a differential expression of particular TCR-Vbeta families and high levels of circulating CD4(+) CD25(high) T cells in long-term surviving renal transplant patients could contribute to an active and specific state of immunologic suppression. However, the increase in this T cell subset with regulatory phenotype can be affected by CNI.

Vaccines for Venezuelan equine encephalitis.

Arboviruses are capable of causing encephalitis in animals and human population when transmitted by the vector or potentially via infectious aerosol. Recent re-emergence of Venezuelan equine encephalitis virus (VEEV) in South America emphasizes the importance of this pathogen to public health and veterinary medicine. Despite its importance no antivirals or vaccines against VEEV are currently available in the USA. Here we review some of the older and newer approaches aimed at generating a safe and immunogenic vaccine as well as most recent data about the mechanistic of protection in animal models of infection.

Activins and inhibins: novel regulators of thymocyte development.

Activins and inhibins are members of the transforming growth factor-beta superfamily that act on different cell types and regulate a broad range of cellular processes including proliferation, differentiation, and apoptosis. Here, we provide the first evidence that activins and inhibins regulate specific checkpoints during thymocyte development. We demonstrate that both activin A and inhibin A promote the DN3-DN4 transition in vitro, although they differentially control the transition to the DP stage. Whereas activin A induces the accumulation of a CD8+CD24(hi)TCRbeta(lo) intermediate subpopulation, inhibin A promotes the differentiation of DN4 to DP. In addition, both activin A and inhibin A appear to promote CD8+SP differentiation. Moreover, inhibin alpha null mice have delayed in vitro T cell development, showing both a decrease in the DN-DP transition and reduced thymocyte numbers, further supporting a role for inhibins in the control of developmental signals taking place during T cell differentiation in vivo.

Flow cytometric analysis of T-lymphocytes from nasopharynx-associated lymphoid tissue (NALT) in a model of secondary immunodeficiency in Wistar rats.

Nasopharynx-associated lymphoid tissue (NALT) is responsible for immune responses in the upper respiratory tract of rodents. In our model of protein malnutrition (R21 group), bronchus-associated lymphoid tissue (BALT), situated in the lower respiratory tract, showed a decrease of CD4(+), CD8alpha(+), and TCRalphabeta(+) lymphocytes but TCRgammadelta(+) cells were increased. Besides, there is no information regarding the frequencies of T-cell populations in 60-day-old Wistar rats (C60 group). So, the aim of the present study was to analyze by flow cytometry NALT T-cells from both groups. NALT lymphocytes were isolated from R21 and C60 groups and stained with different antibodies. Samples were run on a FACScalibur flow cytometer. Background staining was evaluated using isotype controls. Data analysis was performed using BD Cell Quest and WinMDI 2.9. In C60, the predominant population was CD4(+)TCRalphabeta(+), which was significantly diminished in the R21 group. However, CD8alpha(+), the majority expressing CD8alphabeta, and TCRgammadelta(+) cells were not affected. In our model of secondary immunodeficiency, there is a compartmentalization between NALT and BALT because they differ in the populations affected even though they are inductive sites of the respiratory tract in the common mucosal immune system.

Immunoregulatory mechanisms and CD4-CD8- (double negative) T cell subpopulations in human cutaneous leishmaniasis: a balancing act between protection and pathology.

Cellular immune responses directed against protozoan parasites are key for controlling pathogen replication and disease resolution. However, an uncontrolled, or improperly controlled, response can be deleterious to the host in terms of both allowing for the establishment of pathology, as well as less effective establishment of memory responses. Human cutaneous leishmaniasis is a disease caused by the infection with Leishmania spp. following a bite from the sandfly, the natural vector of this disease. Tens of millions worldwide are currently infected with Leishmania and no effective vaccines have been developed to date. In the face of the complexity presented by the interaction between a host (humans) with the parasite, Leishmania, and the fact that this parasite is inoculated by another complex, biologically active, vector, the sandfly, it is clearly important to study the immunoregulatory mechanisms that are induced in humans naturally infected by this parasite if we hope to develop effective vaccines and immunotherapeutic treatments in the future. Our laboratory has focused over the years on the study of the local and systemic T cell response during the first episode of cutaneous leishmaniasis suffered by individuals before they undergo antimony treatment. The goal of this review is to briefly outline our findings with hopes of putting our most recent studies concerning the dichotomy between alpha/beta TCR and gamma/delta TCR expressing, CD4-CD8- (double negative-DN) T cells in the context of a balanced immune response against Leishmania and to discuss the implications of these findings toward our understanding of human leishmaniasis.

Vaccines for multiple sclerosis: progress to date.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS, characterized pathologically by a perivascular infiltrate consisting predominantly of T cells and macrophages. Although its aetiology remains unknown, several lines of evidence support the hypothesis that autoimmune mechanisms play a major role in the development of the disease. Several widely used disease-modifying agents are approved for the treatment of MS. However, these agents are only partially effective and their ability to attenuate the more progressive phases of the disease is not clear at this time. Therefore, there is a need to develop improved treatment options for MS. This article reviews the role of several novel, selective vaccine strategies that are currently under investigation, including: (i) T-cell vaccination (TCV); (ii) T-cell receptor (TCR) peptide vaccination; (iii) DNA vaccination; and (iv) altered peptide ligand (APL) vaccination. The administration of attenuated autoreactive T cells induces regulatory networks to specifically suppress pathogenic T cells in MS, a strategy named TCV. The concept of TCV was based on the experience of vaccination against aetiological agents of infectious diseases in which individuals are purposely exposed to an attenuated microbial pathogen, which then instructs the immune system to recognize and neutralize it in its virulent form. In regard to TCV, attenuated, pathogenic T cells are similarly used to instruct the immune system to recognize and neutralize disease-inducing T cells. In experimental allergic encephalomyelitis (EAE), an animal model for MS, pathogenic T cells use a strikingly limited number of variable-region elements (V region) to form TCR specific for defined autoantigens. Thus, vaccination with peptides directed against these TCR structures may induce immunoregulatory mechanisms, thereby preventing EAE. However, unlike EAE, myelin-reactive T cells derived from MS patients utilize a broad range of different V regions, challenging the clinical utility of this approach. Subsequently, the demonstration that injection of plasmid DNA encoding a reporter gene into skeletal muscle results in expression of the encoded proteins, as well as in the induction of immune responses in animal models of autoimmunity, was explored as another strategy to re-establish self-tolerance. This approach has promise for the treatment of MS and, therefore, warrants further investigation. APLs are molecules in which the native encephalitogenic peptides are modified by substitution(s) of one or a few amino acids critical for contact with the TCR. Depending on the substitution(s) at the TCR contact residues of the cognate peptide, an APL can induce immune responses that can protect against or reverse EAE. However, the heterogeneity of the immune response in MS patients requires further study to determine which patients are most likely to benefit from APL therapy. Other potential approaches for vaccines in MS include vaccination against axonal growth inhibitors associated with myelin, use of dendritic cells pulsed with specific antigens, and active vaccination against proinflammatory cytokines. Overall, vaccines for MS represent promising approaches for the treatment of this devastating disease, as well as other autoimmune diseases.