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Query: UMLS:C0009450 (infectious diseases)
 83,438 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental infection with the intracellular protozoan Leishmania major constitutes a particularly versatile model for assessing the role of CD4+ subset development in the host response to infectious disease. The association of Th1 development with control of infection, and of Th2 cell development with progressive disease, has been well established. The capacity to manipulate the outcome, using distinct immunologic interventions, in both genetically resistant and susceptible mice has identified key effector cytokines that must be present during the time of initial priming of T cells in order to affect the CD4 switch phenotype. Roles for interferon-gamma (IFN-gamma), interleukin 12 (IL-12), and IL-4 in Th1 and Th2 maturation have been demonstrated, although additional undefined signals are required. Study of the genetically susceptible BALB/c mouse has shown failure to downmodulate IL-4 production in response to infection, a response that is critically associated with the failure to develop appropriate Th1 responses. Use of the murine L. major model continues to elucidate new methods for vaccine development and suggests a promising system for identification of genes that determine susceptibility to infection.
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PMID:The regulation of immunity to Leishmania major. 761 19

Kakkon-to is one of the representative traditional herb medicines (Kampo formulae) and has been used historically for the treatment of infectious diseases in China and Japan. The efficacy of this preparation was characterised using a cutaneous herpes simplex virus type 1 (HSV-1) infection in mice as a model for human viral infection. Kakkon-to at a dose corresponding to human use reduced significantly the mortality of HSV-1-infected mice and localised skin lesions. Delayed type hypersensitivity (DTH) response to HSV-1 antigen was significantly stronger in treated mice than in untreated mice. However, no histopathological difference was noted in the skin lesions between treated and untreated mice except for the size of the lesions. Kakkon-to did not inhibit the growth of HSV-1 in vitro. Natural killer cell activity, natural cytotoxic killer cell activity, and the population of T-cell subsets in spleen cells of infected mice were not affected by the drug. Kakkon-to did not augment interferon induction and anti-HSV-1 antibody production, nor increased cytokine levels such as interleukin-1 alpha, interleukin-2, interferon-gamma, and tumour necrosis factor-alpha in sera of infected mice. Thus, Kakkon-to induced strong DTH to HSV-1 in infected mice, which may have caused localisation of skin lesions and reduction in the mortality of treated mice.
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PMID:Efficacy of kakkon-to, a traditional herb medicine, in herpes simplex virus type 1 infection in mice. 762 3

Infection of susceptible mice with murine cytomegalovirus (MCMV) induces persistent inflammation, and the production of autoantibodies reactive with large numbers of proteins from all major organs. However the roles of polyclonal B-cell activation, autoreactive T-helper cells and host-virus cross-reactions in these phenomena have not been evaluated. The present study reveals six- to 20-fold increases in serum immunoglobulin levels in MCMV-infected BALB/c and CBA mice, with IgG3 and IgG2b most affected. Titres of antibodies reactive with autologous tissues and ovalbumin (OVA) also increased following MCMV infection, whilst responses to a synthetic antigen [polyvinyl pyrrolidone (PVP)] were unaffected or depressed. IgG2a was the isotype most affected in responses to OVA, MCMV antigens and autologous tissues, suggesting interferon-gamma (IFN-gamma) may contribute to responses induced in the presence of the relevant antigen. Increases in total and antigen-specific immunoglobulin levels were CD4 dependent, as they were reduced in infected mice depleted of these cells with anti-CD4 antibodies. Serological changes were preceded by B-cell expansion and activation evident from increased cell yields, frequencies of cells releasing immunoglobulin and proliferation of T-depleted spleen and lymph node preparations. Numbers of mature B cells and macrophages increased in the lymph nodes, but B-1a (CD5+ Ig+) cell counts remained low. Alterations in the B-cell phenotypic profiles were more complex in the spleen, but correction for increased cell yields revealed increases in some subpopulations.
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PMID:B-cell activation following murine cytomegalovirus infection: implications for autoimmunity. 767 60

The current understanding of the function of CD4+ T helper (Th) cells in immunity to infectious diseases is that Th1 cells, which secrete interleukin (IL)-2 and interferon-gamma, induce cellular immune responses, whereas Th2 cells, which secrete IL-4, IL-5, IL-6, and IL-10, provide helper function for humoral immunity. We have used a panel of poliovirus-specific murine CD4+ T cell clones and mice transgenic for the human poliovirus receptor to evaluate the role of Th cell subpopulations in protective immunity to poliovirus. The majority of T cell clones, as well as polyclonal T cells generated from mice infected or immunized with poliovirus, secreted IL-2 and interferon-gamma, but not IL-4, IL-5, or IL-10, a profile typical of Th1 cells. The Th1 clones displayed major histocompatibility complex class II-restricted cytotoxic T lymphocyte activity against specific poliovirus peptide-pulsed target cells, but also provided help for antipoliovirus neutralizing antibody production. To examine the mechanism of immunity in vivo, we have used poliovirus receptor-transgenic mice on a BALB/c (H-2d) background. These animals developed a poliomyelitis-like disease when challenged intravenously with a virulent wild-type strain of poliovirus, but not with an attenuated vaccine strain. Furthermore, mice immunized with the vaccine strain were protected against a subsequent challenge with wild-type virus. Using an adoptive transfer technique, we demonstrated that it was possible to confer protection with primed B cells in the presence of polyclonal poliovirus-specific T cells, but not when transgenic mice received either B cells or T cells alone. Furthermore, protection was observed when mice received primed B cells in the presence of a VP4-specific Th1 clone. The findings demonstrate that Th1 cells can mediate a protective immune response against poliovirus infection in vivo through helper activity for humoral immunity and that CD4+ T cells, specific for the internal poliovirus capsid protein, VP4, can provide effective help for a protective antibody response directed against surface capsid proteins.
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PMID:Poliovirus-specific CD4+ Th1 clones with both cytotoxic and helper activity mediate protective humoral immunity against a lethal poliovirus infection in transgenic mice expressing the human poliovirus receptor. 769 20

Distinct patterns of T cell cytokine production have been shown to influence the outcome of infection in mouse models and humans. Th1 or Type 1 cytokines, interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) are generally associated with resistance to infection, whereas Th2 or Type 2 cytokines, IL-4 and IL-10 are associated with progressive disease. Leprosy is a useful model for studying the role of cytokines in modulating T cell responses in human infectious disease. Infection by Mycobacterium leprae results in disease manifestations that encompass an immunological spectrum. Tuberculoid patients are able to restrict the growth of the pathogen and mount strong T cell responses to M. leprae. In contrast, lepromatous patients manifest disseminated infection and their T cells weakly respond to M. leprae. We have found that tuberculoid leprosy lesions have a predominance of CD4+ T cells producing the Type 1 cytokine pattern. Secondly, IL-12 mRNA was expressed at 10-fold higher levels in tuberculoid lesions as compared to lepromatous lesions and that IL-12 promotes the selective expansion of the Type 1 cytokine producing cells. In contrast, lepromatous lesions contain CD8+ IL-4-producing cells that suppress antigen-specific T cell responses and promote the outgrowth of additional suppressor T cells. IL-10, also expressed at higher levels in lepromatous as compared to tuberculoid lesions, was found to be produced by macrophages, effectively inhibiting cytokine production and macrophage activity.
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PMID:Cytokine patterns at the site of mycobacterial infection. 771 51

We present the case of a 16-year-old girl with p22-deficient chronic granulomatous disease in whom multiple hepatic abscesses secondary to Staphylococcus aureus infection developed. Infection persisted despite extensive surgery and aggressive antibiotic therapy. Conventional intravenous granulocyte transfusions were not tolerated because of the development of alloantibodies to HLA. Treatment with interferon-gamma and intralesional granulocyte infusions was associated with dramatic clinical and radiographic improvement. No morbidity was associated with this therapy. To our knowledge, this is the first report of treatment with intralesional granulocyte instillations. Intralesional granulocyte instillation in association with interferon-gamma administration may result in clinical improvement in the conditions of patients with chronic granulomatous disease and hepatic abscesses for whom conventional therapy has failed.
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PMID:Treatment with intralesional granulocyte instillations and interferon-gamma for a patient with chronic granulomatous disease and multiple hepatic abscesses. 780 48

Infection with human parvovirus B19 induces a biphasic disease. The initial phase has been associated with viremia. During the second phase of the disease, a spectrum of clinical syndromes can manifest, including erythema infectiosum, perinatal complications, and symmetric arthropathy that resembles rheumatoid arthritis. Although investigators have suspected that some of the second-phase symptoms are related to immune complex formation, the pathogenesis of parvovirus B19-induced clinical manifestations is not understood. Herein we describe a 63-year-old woman with malaise, fever, and symmetric polyarthritis who had IgM antibodies specific for parvovirus B19. Messenger RNA (mRNA) specific for interleukin (IL) 1 beta, IL 6, and interferon-gamma (IFN-gamma) was detected by polymerase chain reaction. Transcript concentrations were semiquantified by serial dilution of cells and determination of the minimal number of cells that provided a positive signal. Concentrations of IL 1 beta and IL 6 mRNA in peripheral blood mononuclear cells collected during acute disease were increased by the factor of 32 and 8, respectively. IFN-gamma was detected at a 16-fold increased concentration. Two months later, after the patient had experienced complete recovery, production of monokines and IFN-gamma was almost normalized. These data raise the possibility that acute parvovirus B19 infection is characterized by a widespread and systemic activation of monocytes, T cells, and natural killer cells. The correlation of increased cytokine mRNA levels and clinical symptoms suggests a potential role of proinflammatory monokines and lymphokines in disease manifestations.
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PMID:Systemic monocyte and T-cell activation in a patient with human parvovirus B19 infection. 786 14

Interleukin 12 (IL-12), a heterodimeric cytokine composed of p40 and p35 chains, has potent immunologic effects in vitro. We used tuberculous pleuritis as a model to study the immunoregulatory potential of IL-12 in vivo at the site of human infectious disease. Messenger RNAs for p40 and p35 were detected in pleural fluid from six of six patients by reverse-transcription polymerase chain reaction. By using an ELISA that detected both free p40 and heterodimeric IL-12, we found that mean concentrations were 585 +/- 89 pg/ml in pleural fluid of patients with tuberculous pleuritis, which were significantly higher than those in serum of the same patients (54 +/- 36 pg/ml), or in malignant pleural effusions (123 +/- 35 pg/ml). By using an ELISA specific for heterodimeric IL-12, we found that mean concentrations in pleural fluid of patients with tuberculous pleuritis were 165 +/- 28 pg/ml and undetectable in serum of the same patients, or in malignant pleural effusions. Bioactive IL-12 was detectable in five of five supernatants of pleural fluid cells stimulated with Mycobacterium tuberculosis. Addition of anti-IL-12 antibodies suppressed proliferative responses of pleural fluid cells to M. tuberculosis by 36 +/- 7%. These data indicate that IL-12 may play a role in the human immune response to infectious agents in vivo. We hypothesize that IL-12 contributes to the antimycobacterial immune response by enhancing production of interferon-gamma, facilitating development of Th1 cells and augmenting cytotoxicity of antigen-specific T cells and natural killer cells.
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PMID:Interleukin 12 at the site of disease in tuberculosis. 790 20

The influence of Trichinella spiralis on infections with Trichuris muris was studied in non-responder B10.BR mice. Mice infected only with T. muris were unable to expel parasites and had many adult worms 35 days later. Infection with 300 larvae of T. spiralis, given seven or 14 (but not 28) days after T. muris, enabled mice to expel up to 90% of T. muris; expulsion of T. spiralis was not altered. Concurrently infected mice produced less T. muris-specific IgG2a antibody than mice infected with T. muris only, and showed higher proliferative responses when spleen and mesenteric lymph node cells were cultured in vitro with T. muris antigens. When T. spiralis was present mucosal mast cells were generated in T. muris-infected mice, whereas almost no mast cells were seen with only T. muris. Lymphocytes from doubly-infected mice produced significantly more interleukin 4 and 5 (IL-4, IL-5) and significantly less interferon-gamma (IFN-gamma) when stimulated in vitro with Concanavalin A (Con-A) than cells from mice infected with T. muris only. These data demonstrate that B10.BR mice, which in single infections produce a Th1 response to T. muris and develop no protective immunity, can mount a protective T-helper-2 (Th2) response and expel T. muris when concurrently infected with the 'Th2-inducing' nematode T. spiralis.
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PMID:Lymphocyte, antibody and cytokine responses during concurrent infections between helminths that selectively promote T-helper-1 or T-helper-2 activity. 801 54

Infection with a virulent strain of Mycobacterium avium, but not with virulent Mycobacterium tuberculosis or avirulent Mycobacterium smegmatis, induced the formation of nitric oxide by human monocyte-derived macrophages. This process was not affected by lipopolysaccharide or cytokines such as interferon-gamma or tumor necrosis factor alpha. M. avium-induced nitric oxide production was significantly decreased by NG-monomethyl-L-arginine, a potent inhibitor of nitric oxide synthase activity, without any significant enhancement of intramacrophagic mycobacterial growth. Infection with all the three mycobacterial species induced a significant activation of phospholipase A2 activity of macrophages as evidenced by the increased release of thromboxane A2. Finally, nitric oxide production by human monocyte-derived macrophages required infection with live M. avium, as neither gamma-irradiated M. avium nor the subcellular fractions of this microorganism (cell wall, cytosol) were able to trigger nitric oxide synthesis.
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PMID:Selective Mycobacterium avium-induced production of nitric oxide by human monocyte-derived macrophages. 802 68


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