Subdominant H60 antigen-specific CD8 T-cell response precedes dominant H4 antigen-specific response during the initial phase of allogenic skin graft rejection

In allogeneic transplantation, including the B6 anti-BALB.B settings, H60 and H4 are two representative dominant minor histocompatibility antigens that induce strong CD8 T-cell responses. With different distribution patterns, H60 expression is restricted to hematopoietic cells, whereas H4 is ubiquitously expressed. H60-specific CD8 T-cell response has been known to be dominant in most cases of B6 anti-BALB.B allo-responses, except in the case of skin transplantation. To understand the mechanism underlying the subdominance of H60 during allogeneic skin transplantation, we investigated the dynamics of the H60-specific CD8 T cells in B6 mice transplanted with allogeneic BALB.B tail skin. Unexpectedly, longitudinal bioluminescence imaging and flow cytometric analyses revealed that H60-specific CD8 T cells were not always subdominant to H4-specific cells but instead showed a brief dominance before the H4 response became predominant. H60-specific CD8 T cells could expand in the draining lymph node and migrate to the BALB.B allografts, indicating their active participation in the anti-BALB.B allo-response. Enhancing the frequencies of H60-reactive CD8 T cells prior to skin transplantation reversed the immune hierarchy between H60 and H4. Additionally, H60 became predominant when antigen presentation was limited to the direct pathway. However, when antigen presentation was restricted to the indirect pathway, the expansion of H60-specific CD8 T cells was limited, whereas H4-specific CD8 T cells expanded significantly, suggesting that the temporary immunodominance and eventual subdominance of H60 could be due to their reliance on the direct antigen presentation pathway. These results enhance our understanding of the immunodominance phenomenon following allogeneic tissue transplantation.

Las células guardianes residentes de la piel y su papel en la respuesta inmune. Parte 1 / Cells resident guardians of the skin and its role in the immune response

La piel constituye la primera barrera del sistema inmune contra potenciales agentes patógenos y nocivos externos. Evidencia importante sugiere que las células inmunológicas requieren de funciones conjuntas con los queratinocitos, para alertar y ensamblar una respuesta inmune adecuada, que incluye la formación del sistema de alerta denominado inflamosoma. Adicionalmente, nuevos fenotipos funcionales de células presentadoras de antígenos (CPA) en la piel como las células dendríticas han demostrado tener gran importancia en ensamblar la respuesta inmune incluso mayor que las células T circulantes. La primera entrega de este artículo describe la funcionalidad de los queratinocitos y las células dendriticas en la piel, para en la segunda parte discriminar sus roles juntos a los linfocitos T y las fallas de la regulación durante las interacciones en la formaión del inflamosoma.

Human skin is the first shield which provides essential protection of the human body from injury and infection. Important evidence reinforces the importance of keratinocytes as sensors of danger through alert systems such as the inflammasome and key components in the appropriate immune response. In addition, newly identified antigen-presenting cells (APCs), as dendritic cells, have demonstrated to have a key role of assembling the immune response even major than circulating T cells in skin. The first part of this review focuses on dissecting the functional role of keratinocytes and dendritic cells in skin in order to, in the second part, analyze their roles and interactions together with the T lymphocytes during the inflammasome formation.

Newer targeted therapies in psoriasis.

Psoriasis is a common, chronic, inflammatory skin disease that can have a significant impact on the quality of life of those who are afflicted due to chronicity of the disease and frequent remissions and relapses. Many available systemic therapies, however, are unsuitable for chronic administration due to the risk of cumulative toxicity. Recent advances in the understanding of the pathophysiology of psoriasis have led to the development of new, genetically engineered, targeted therapies for this disease. These include approaches targeting antigen presentation and co-stimulation, T-cell activation and leukocyte adhesion, action on pro-inflammatory mediators, and modulating the cytokine balance. Although only preliminary data are available so far and there is limited data supporting their use, these trials contribute to a further understanding of the disease and will eventually lead to new therapeutic options for psoriasis.

Newer targeted therapies in psoriasis.

Psoriasis is a common, chronic, inflammatory skin disease that can have a significant impact on the quality of life of those who are afflicted due to chronicity of the disease and frequent remissions and relapses. Many available systemic therapies, however, are unsuitable for chronic administration due to the risk of cumulative toxicity. Recent advances in the understanding of the pathophysiology of psoriasis have led to the development of new, genetically engineered, targeted therapies for this disease. These include approaches targeting antigen presentation and co-stimulation, T-cell activation and leukocyte adhesion, action on pro-inflammatory mediators, and modulating the cytokine balance. Although only preliminary data are available so far and there is limited data supporting their use, these trials contribute to a further understanding of the disease and will eventually lead to new therapeutic options for psoriasis.

Antigen-presenting cells transfected with Hsp65 messenger RNA fail to treat experimental tuberculosis

In the last several years, the use of dendritic cells has been studied as a therapeutic strategy against tumors. Dendritic cells can be pulsed with peptides or full-length protein, or they can be transfected with DNA or RNA. However, comparative studies suggest that transfecting dendritic cells with messenger RNA (mRNA) is superior to other antigen-loading techniques in generating immunocompetent dendritic cells. In the present study, we evaluated a new therapeutic strategy to fight tuberculosis using dendritic cells and macrophages transfected with Hsp65 mRNA. First, we demonstrated that antigen-presenting cells transfected with Hsp65 mRNA exhibit a higher level of expression of co-stimulatory molecules, suggesting that Hsp65 mRNA has immunostimulatory properties. We also demonstrated that spleen cells obtained from animals immunized with mock and Hsp65 mRNA-transfected dendritic cells were able to generate a mixed Th1/Th2 response with production not only of IFN-γ but also of IL-5 and IL-10. In contrast, cells recovered from mice immunized with Hsp65 mRNA-transfected macrophages were able to produce only IL-5. When mice were infected with Mycobacterium tuberculosis and treated with antigen-presenting cells transfected with Hsp65 mRNA (therapeutic immunization), we did not detect any decrease in the lung bacterial load or any preservation of the lung parenchyma, indicating the inability of transfected cells to confer curative effects against tuberculosis. In spite of the lack of therapeutic efficacy, this study reports for the first time the use of antigen-presenting cells transfected with mRNA in experimental tuberculosis.

Induction of Donor-Specific Tolerance: Is This Achievable?

No abstract available.

Prolonged expression of MHC class I - peptide expression in bone marrow derived retrovirus transfected matured dendritic cells by continuous centrifugation in the presence of IL-4.

Background & objectives: Dendritic cells (DCs) are potent antigen presenting cells which proceed from immature to a mature stage during their differentiation. There are several methods of obtaining long lasting mature antigen expressing DCs and different methods show different levels of antigen expressions. We investigated bone marrow derived DCs for the degree of maturation and genetically engineered antigen presentation in the presence of interleukin-4 (IL-4) as a maturity enhancer. Methods: DCs and transfected retrovirus were cultured together in the presence of granulocyte-macrophage colony stimulating factor (GMCSF)-IL4, GMCSF +IL4, lipopolysaccharide (LPS). B 7.1, B7.2 and CD11c were measured by the degree of immune fluorescence using enhanced green fluorescent protein (EGFP) shuttled retrovirus transfected antigen. Degree of MHC class I molecule with antigen presentation of antigen was also evaluated by fluorescence activated cell sorting. The antigen presenting capacity of transfected DCs was investigated. Bone marrow DCs were generated in the presence of GMCSF and IL-4 in vitro. Dividing bone marrow cells were infected with EGFP shuttled retrovirus expressing SSP2 by prolonged centrifugation for three consecutive days from day 5, 6 and 7 and continued to culture in the presence of GMSCF and IL-4 until day 8. Results: IL-4 as a cytokine increased the maturation of retrovirus transfected DCs by high expression of B 7-1 and B 7-2. Also, IL-4 induced DC enhanced by the prolonged centrifugation and it was shown by increased antigen presentation of these dendric cells as antigen presenting cell (APC). Cytolytic effects were significantly higher in cytotoxic T cell response (CTLs) mixed with transfected DCs than CTLs mixed with pulsed DCs. Interpretation & conclusions: There was an enhanced antigen presentation by prolonged expression of antigen loaded MHC class I receptors in DCs in the presence of IL-4 by prolonged centrifugation.

The requirement of natural killer T-cells in tolerogenic APCs-mediated suppression of collagen-induced arthritis

TGF-beta-induced tolerogenic-antigen presenting cells (Tol-APCs) could induce suppression of autoimmune diseases such as collagen-induced arthritis (CIA) and allergic asthma. In contrast, many studies have shown that NKT cells are involved in the pathogenesis of Th1-mediated autoimmune joint inflammation and Th2-mediated allergic pulmonary inflammation. In this study, we investigated the effect of CD1d-restricted NKT cells in the Tol-APCs-mediated suppression of autoimmune disease using a murine CIA model. When CIA-induced mice were treated with Tol-APCs obtained from CD1d+/- or CD1d-/- mice, unlike CD1d+/- APCs, CD1d-/- Tol-APCs failed to suppress CIA. More specifically, CD1d-/- Tol-APCs failed to suppress the production of inflammatory cytokines and the induction of Th2 responses by antigen-specific CD4 T cells both in vitro and in vivo. Our results demonstrate that the presence of CD1d-restricted NKT cells is critical for the induction of Tol-APCs-mediated suppression of CIA.

B-1 cell: the precursor of a novel mononuclear phagocyte with immuno-regulatory properties

Characterization of the origin, properties, functions and fate of cells is a fundamental task for the understanding of physiological and pathological phenomena. Despite the bulk of knowledge concerning the diverse characteristics of mammalian cells, some of them, such as B-1 cells, are still poorly understood. Here we report the results obtained in our laboratory on these cells in the last 10 years. After showing that B-1 cells could be cultured and amplified in vitro, a series of experiments were performed with these cells. They showed that B1 cells reside mostly in the peritoneal and pleural cavities, migrate to distant inflammatory foci, coalesce to form giant cells and participate in granuloma formation, both in vitro and in vivo. They are also able to present antigens to immunologically responsive cells and are endowed with regulatory properties. Further, we have also shown that these cells facilitate different types of infection as well as tumor growth and spreading. These data are presently reviewed pointing to a pivotal role that these cells may play in innate and acquired immunity.

A caracterização da origem, propriedades, funções e destino das células representam objetivo fundamental para a compreensão dos fenômenos fisiológicos e patológicos. Apesar da grande quantidade de conhecimentos relativos às diversas características das células de mamíferos, muitas delas, inclusive células B-1, são pouco entendidas. Depois de mostrar que as células B-1 podem ser cultivadas e amplificadas in vitro, uma série de experimentos visando esclarecer as propriedades dessas células puderam ser feitos em nosso laboratório nos últimos 10 anos. Assim, pudemos demonstrar que células B-1 residem principalmente nas cavidades peritoneal e pleural do camundongo, migram para focos inflamatórios distantes, coalescem para formar células gigantes e participam na formação de granulomas, tanto in vitro como in vivo. São também capazes de apresentar antígenos a células responsivas e são dotadas de propriedades imuno-regulatórias. Mostramos ainda que estas células favorecem diferentes tipos de infecções bem como o crescimento e metastatização tumoral. Esses resultados sugerem que células B-1 devem exercer papel central na imunidade como um todo.

Differential gene expression profiles of human monocyte-derived antigen presenting cells in response to Penicillium marneffei: roles of DC-SIGN (CD209) in fungal cell uptake.

DNA microarray technology was used to determine the gene expression profile of human monocyte-derived macrophages (hMDMs) after stimulation by Penicillium marneffei yeast. The expression levels of 175 macrophage genes were found to be altered by a minimum of two-fold in magnitude following 4 hours of P. marneffei exposure. Among those, 41 genes were upregulated in activated hMDMs while 134 genes were downregulated. Real-time PCR and RT-PCR were performed to further examine gene expression associated with the inflammatory response. Increased levels of TNF-alpha and IL-1 beta gene expression in both hMDMs and human monocyte-derived dendritic cells (hMoDCs) were observed after stimulation by P. marneffei yeast. Furthermore, the genes encoding T-bet, IL-6 and ICAM-1 were also upregulated in hMDMs. Functional analysis of the adhesion of P. marneffei to dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN, CD209) was performed in hMoDCs since the microarray data revealed an increased expression of DC-SIGN in activated hMDMs. We found that DC-SIGN-Fc bound preferentially to P. marneffei yeast rather than to conidia. Moreover, an anti-DC-SIGN monoclonal antibody inhibited the binding of P. marneffei yeast to hMoDCs, but did not inhibit endocytosis of P. marneffei yeast. The mannose receptor, on the other hand, was important in both adhesion and phagocytosis. These results suggest that P. marneffei may exploit DC-SIGN as a receptor to facilitate the systemic spread of infection. Taken together, our study demonstrates the usefulness of microarray technology in generating valuable expression data to permit conventional immunologic investigations of host-fungal interactions.

Low expression of antigen-presenting and costimulatory molecules by lung cells from tuberculosis patients

Costimulatory and antigen-presenting molecules are essential to the initiation of T cell immunity to mycobacteria. The present study analyzed by immunocytochemistry, using monoclonal antibodies and alkaline phosphatase-anti-alkaline phosphatase method, the frequency of costimulatory (CD86, CD40, CD40L, CD28, and CD152) and antigen-presenting (MHC class II and CD1) molecules expression on human lung cells recovered by sputum induction from tuberculosis (TB) patients (N = 22) and non-TB controls (N = 17). TB cases showed a statistically significant lower percentage of HLA-DR+ cells than control subjects (21.9 ± 4.2 vs 50.0 ± 7.2 percent, P < 0.001), even though similar proportions of TB cases (18/22) and control subjects (16/17, P = 0.36) had HLA-DR-positive-stained cells. In addition, fewer TB cases (10/22) compared to control subjects (16/17) possessed CD86-expressing cells (P = 0.04; OR: 0.05; 95 percentCI = 0.00-0.51), and TB cases expressed a lower percentage of CD86+ cells (P = 0.04). Moreover, TB patients with clinically limited disease (£1 lobe) on chest X-ray exhibited a lower percentage of CD86-bearing cells compared to patients with more extensive lung disease (>1 lobe) (P = 0.02). The lower expression by lung cells from TB patients of HLA-DR and CD86, molecules involved in antigen presentation and activation of T cells, may minimize T cell recognition of Mycobacterium tuberculosis, fostering an immune dysfunctional state and active TB.

Factors affecting the presentation of exogenous hepatitis B virus core antigen.

Hepatitis B virus core antigen (HBcAg) plays a critical role in terminating acute Hepatitis B virus infection and may be used as a potential vaccine candidate. The cell surface major histocompatibility complex (MHC) class 1 molecules are thought to be involved in the presentation of HBcAg. Surface MHC class 1 HLA A2 heavy chain (HC) and trimeric molecules were characterized on transfected Hela cells used as antigen presenting cells (APC) for the presentation of HBcAg. The results show that antibodies against HC HLA A2 and trimeric HLA-A2 molecules resulted in increased activation of HBcAg 18-27 minimal peptide specific cytotoxic T lymphocytes (CTLs), while the addition of exogenous beta2-microglobulin decreased the activation of HBcAg specific CTLs. Further, specific CD8+ T cells were activated only when Hela cells as APCs were primed with HBcAg (peptide, soluble or embedded on virosomes) at pH 6.5.

Efficient amplification of melanoma-specific CD8+ T cells using artificial antigen presenting complex

In vitro large amplification of tumor-specific cytotoxic T lymphocytes (CTLs) and adoptive transfer of these cells is one of the most promising approaches to treat malignant diseases in which an effective immune response is not achieved by active immunization. However, generating sufficient numbers of tumor-specific CTLs stimulated with autologous antigen presenting cells (APCs) in vitro is one of the most problematic steps in the adoptive cell transfer (ACT) therapy. To circumvent this problem, we have developed an artificial antigen presenting complex (aAPCs) using MHC class I molecules loaded with a melanoma-specific TRP-2 peptide epitope. Our results show that TRP-2-specific CD8+ T cells elicited by immunization with recombinant adenovirus expressing the mini-gene epitope are efficiently stimulated and amplified in vitro to a greater extent by aAPCs than by natural splenic APCs. These aAPC-induced CTLs recognized endogenously processed antigens present on B16F10 melanoma cells. Efficient stimulation and proliferation of antigen- specific T cells was also confirmed using ovalbumin peptide-loaded aAPCs and OT-I TCR transgenic cells. These results demonstrate that prior in vivo immunization, which increases the precursor frequency, simplifies posterior expansion of tumor- specific CD8+ T cells, and aAPCs is superior to autologous APC for in vitro amplification. This prime and expand regimen can be an alternative method for large amplification of rare tumor-specific CTLs and aAPCs should be a useful tool for ACT immunotherapy.

Immunology of tuberculosis.

Tuberculosis is a major health problem throughout the world causing large number of deaths, more than that from any other single infectious disease. The review attempts to summarize the information available on host immune response to Mycobacterium tuberculosis. Since the main route of entry of the causative agent is the respiratory route, alveolar macrophages are the important cell types, which combat the pathogen. Various aspects of macrophage-mycobacterium interactions and the role of macrophage in host response such as binding of M. tuberculosis to macrophages via surface receptors, phagosome-lysosome fusion, mycobacterial growth inhibition/killing through free radical based mechanisms such as reactive oxygen and nitrogen intermediates; cytokine-mediated mechanisms; recruitment of accessory immune cells for local inflammatory response and presentation of antigens to T cells for development of acquired immunity have been described. The role of macrophage apoptosis in containing the growth of the bacilli is also discussed. The role of other components of innate immune response such as natural resistance associated macrophage protein (Nramp), neutrophils, and natural killer cells has been discussed. The specific acquired immune response through CD4 T cells, mainly responsible for protective Th1 cytokines and through CD8 cells bringing about cytotoxicity, also has been described. The role of CD-1 restricted CD8(+) T cells and non-MHC restricted gamma/deltaT cells has been described although it is incompletely understood at the present time. Humoral immune response is seen though not implicated in protection. The value of cytokine therapy has also been reviewed. Influence of the host human leucocyte antigens (HLA) on the susceptibility to disease is discussed. Mycobacteria are endowed with mechanisms through which they can evade the onslaught of host defense response. These mechanisms are discussed including diminishing the ability of antigen presenting cells to present antigens to CD4(+) T cells; production of suppressive cytokines; escape from fused phagosomes and inducing T cell apoptosis. The review brings out the complexity of the host-pathogen interaction and underlines the importance of identifying the mechanisms involved in protection, in order to design vaccine strategies and find out surrogate markers to be measured as in vitro correlate of protective immunity.

Imunopatologia da hanseníase: a complexidade dos mecanismos da resposta imune do hospedeiro ao Mycobacterium leprae / Immunopathology of leprosy: the complexity of the mechanisms of host immune response to Mycobacterium leprae

Leprosy, whose etiologic agent Mycobacterium leprae, is an illness of ample clinical and immunopathological spectrum. Its clinical manifestations are correlated with distinct immunologic forms, varying from a vigorous immune response mediated by cells to M. leprae, with Th1 standard in the tuberculoid polar region, to an absence of specific cellular response to antigens of M. leprae in the lepromatous polar region, with predominance of Th2 response and exacerbation of humoral response. It is probable that different polymorphic genes determine susceptibility to M. leprae. Additional studies are necessary to clarify the complex interactions between cytokines and the role of the phenotypic diversity of cells network that contribute to the host defense. The comprehension of such mechanisms will provide new insights for the identification of agonists and/or antagonists for pro- or anti-inflammatory effects, and also will indicate possible situations for its appropriate use in immunologic and/or immunotherapeutic interventions.

The low efficiency of dendritic cells and macrophages from mice susceptible to Paracoccidioides brasiliensis in inducing a Th1 response

In the present study we evaluated T cell proliferation and Th lymphokine patterns in response to gp43 from Paracoccidioides brasiliensis presented by isolated dendritic cells from susceptible and resistant mice. T cell proliferation assays showed that dendritic cells from susceptible mice were less efficient than those from resistant mice. The pattern of T cell lymphokines stimulated by dendritic cells was always Th1, although the levels of IL-2 and IFN-gamma were lower in T cell cultures from susceptible mice. To determie whether different antigen-presenting cells such as macrophages and dendritic cells stimulated different concentrations of Th1 lymphokines, the production of IFN-gamma and IL-2 was measured. It was observed that dendritic cells were more efficient than macrophages in stimulating lymphoproliferation in resistant mice. However, no significant difference was observed for IFN-gamma or IL-2 production. When cells from susceptible mice were used, macrophages were more efficient in stimulating lymphoproliferation than dendritic cells, but no difference was observed in the production of Th1 cytokine. Taken together, these results suggest the lower efficiency of dendritic cells and macrophages from B10.A mice in stimulating T cells that secrete Th1 lymphokines in vitro, an effect that may be involved in the progression of the disease in vivo

Obtention of rabies antigen through BHK21 cells adhered to microcarriers

Foram produzidos quatro lotes de antigeno rabico a partir de suspensoes de virus resultantes de celulas BHK21 infectadas, aderidas a microcarregadores do tipo Cytodex 1 e cultivadas em biorreator. Em paralelo foi utilizada a metodologia de producao de virus rabico com celulas BHK21 em monocamadas, contidas em garrafas de 350cm2. Os resultados encontrados demonstraram que os titulos infectantes foram de 10 elevado a 6.69 DL50/mL para as suspensoes virais obtidas em garrafas e 10 elevado a 7.28 DL50/mL para as do biorreator. Os volumes das suspensoes virais colhidas foram, em media de 11.900 mL por lote do biorreator e 800 mL por garrafa. Com o antigeno produzido no biorreator foram imunizados 10 cavalos. As medias dos titulos de anticorpos anti-rabicos encontrados nos soros destes animais foram de 240 e 212 UI/mL, respectivamente apos a base e o primeiro reforco. Atraves da infeccao de celulas BHK21 aderidas, a microcarregadores e cultivadas em biorreator, pode-se obter antigeno rabico em larga escala e com titulos infectantes satisfatorios

The immunology of nickel-induced allergic contact dermatitis.

Attempts have been made to elucidate the immunopathogenesis of contact allergy; yet, the exact mechanism by which nickel-induced allergic contact dermatitis (NACD) occurs is far from clear and is discussed herein. It seems to suggest that a direct nickel-MHC class II molecule binding on the skin antigen presenting cells such as Langerhans cells (LCs) would result in Th1 cell activation. Substances such as serotonin and cytokines such as TNF-alpha produced by activated mast cells may increase adhesion molecule expression and thus, enhance T cell trafficking in the skin. Cytokines such as IFN-gamma and IL-1 and perhaps IL-12 certainly play a crucial role in the activation of Th1 cells. Along with possible function of CD8 cells, downregulation of NACD may be mediated by suppressed function of LCs via the action of activated keratinocytes-derived IL-10. Inhibition of NACD can also be generated by feeding with nickel, suggesting that the induction of oral tolerance to nickel may be beneficial for an alternative immunotherapy of nickel allergy. Nevertheless, this testable model provides a direction for further investigation.