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At least 343 records · Page 19Linked to original sources
PubMed2005

Measuring T-cell function in animal models of tuberculosis by ELISPOT.

Enzyme-linked immunospot (ELISPOT) was originally developed from an enzyme-linked immunosorbent assay (ELISA) to detect and measure the frequency of individual cells that produce cytokines in response to antigenic stimulation. ELISPOT assay is more sensitive than the enzyme-linked immunosorbent assay or intracellular cytokine staining. Increased sensitivity of ELISPOT is particularly advantageous when studying T-cell-mediated responses in Mycobacterium tuberculosis infection because antigen specific T-cells can occur at a low frequency in vivo. This method has been successfully used to analyze M. tuberculosis immune responses in humans in addition to murine and nonhuman primate models of tuberculosis.

Animals↗
PubMed1978

The lymphocyte mediators of delayed hypersensitivity: the early phase cells.

Inbred rats were immunized with living BCG and lymphocytes which mediate tuberculin DTH and anti-tuberculosis immunity were found 10 days later in the draining lymph nodes, thoracic duct, blood, spleen and acute peritoneal exudates. The lymphocytes that mediated DTH incorporated 3HT in vitro, were large in size, sensitive to vinblastine but relatively resistant to irradiation, and had a short effective lifespan in syngeneic recipients. These properties characterize the cells as short-lived, nonrecirculating immunoblasts. In some experimental situations it was possible to dissociate the expression of DTH and immunity following the transfer of sensitized lymphocytes.

Animals↗
PubMed1999

Lymphocytotoxic antibodies & immunity in pulmonary tuberculosis.

To understand whether the presence of cold reactive lymphocytotoxic antibodies (LCA) (reactive at 15 degrees C) in the system has any effect on immunity to tuberculosis lymphocytotoxic antibodies to adherent cells (enriched-B cells) and non-adherent cells were studied in active-TB (n = 42) and inactive-TB (cured) patients (n = 49) and healthy controls (n = 32). The plasma samples of inactive-TB patients showed higher percentage of positivity for lymphocytotoxic antibodies (36.7%) than the active-TB patients (21.4%) and control subjects (18.8%). No significant difference on antibody and lymphocyte response against Mycobacterium tuberculosis culture filtrate antigens was observed between LCA positive and LCA negative active-TB patients and normal healthy controls. Further, determination of HLA-DR phenotype of the patients and control subjects showed that individuals positive for lymphocytotoxic antibodies were more among HLA-DR2 positive and DR7 positive active-TB patients and control subjects than non-DR2 and non-DR7 subjects. The present study suggests that the cold reactive lymphocytotoxic antibodies may be against B-lymphocytes and persistent for a longer time. HLA-DR2 and -DR7 may be associated with the occurrence of LCA activity. Further, the presence of LCA has no immunoregulatory role on immunity to tuberculosis.

Adult↗
PubMed1992

Immunization with extracellular proteins of Mycobacterium tuberculosis induces cell-mediated immune responses and substantial protective immunity in a guinea pig model of pulmonary tuberculosis.

We have studied the capacity of a selected fraction of Mycobacterium tuberculosis extracellular proteins (EP) released into broth culture by mid-logarithmic-growth-phase organisms to induce cell-mediated immune responses and protective immunity in a guinea pig model of pulmonary tuberculosis. Guinea pigs infected with M. tuberculosis by aerosol but not uninfected control guinea pigs exhibit strong cell-mediated immune responses to EP, manifest by dose-dependent cutaneous delayed-type hypersensitivity and splenic lymphocyte proliferation. Guinea pigs immunized subcutaneously with EP but not sham-immunized control guinea pigs also develop strong cell-mediated immune responses to EP, manifest by dose-dependent cutaneous delayed-type hypersensitivity and splenic lymphocyte proliferation. EP is nonlethal and nontoxic to guinea pigs upon subcutaneous immunization. Guinea pigs immunized with EP and then challenged with aerosolized M. tuberculosis exhibit protective immunity. In five independent experiments, EP-immunized guinea pigs were consistently protected against clinical illness, including weight loss. Compared with EP-immunized guinea pigs, sham-immunized control guinea pigs lost 12.9 +/- 2.0% (mean +/- SE) of their total weight. EP-immunized guinea pigs also had a 10-fold reduction in viable M. tuberculosis bacilli in their lungs and spleens (P = 0.004 and 0.001, respectively) compared with sham-immunized control animals. In the two experiments in which some guinea pigs died after aerosol challenge, EP-immunized animals were protected from death. Whereas all 12 (100%) EP-immunized guinea pigs survived challenge with aerosolized M. tuberculosis, only 6 of 12 (50%) sham-immunized control guinea pigs survived challenge (P = 0.007, Fisher exact test). This study demonstrates that actively growing M. tuberculosis cells release immunoprotective molecules extracellularly, that a subunit vaccine against tuberculosis is feasible, and that extracellular molecules of M. tuberculosis are potential candidates for a subunit vaccine.

Aerosols↗
PubMed1999

Dietary linoleic acid, immune inhibition and disease.

Review of the evidence available in published literature supports a radical change in viewpoint with respect to disease in countries where maize is the predominant dietary component. In these countries, the pattern of disease is largely determined by a change in immune profile caused by metabolites of dietary linoleic acid. High intake of linoleic acid in a diet deficient in other polyunsaturated fatty acids and in riboflavin results in high tissue production of prostaglandin E2, which in turn causes inhibition of the proliferation and cytokine production of Th1 cells, mediators of cellular immunity. Tuberculosis, measles, hepatoma, secondary infection in HIV and kwashiorkor are all favoured by this reduction in cellular immunity. Diet-associated inhibition of the Th1 subset is a major contributor to the high prevalence of these diseases found in areas of sub-Saharan Africa where maize is the staple.

Africa↗
PubMed1976

Rifampin and cell-mediated immune responses in tuberculosis.

To estimate the potential adverse consequences of rifampin therapy on cell-mediated immunity in tuberculosis, we measured in vitro lymphocyte responses to phytohemagglutinin, concanavalin A, pokeweed mitogen, and in vitro and in vivo responses to purified protein derivative tuberculin. Thirty-seven patients treated with therapeutic combinations containing rifampin were compared with 13 persons who had never received the drug. After initial improvement, responses to phytohemagglutinin became depressed in patients receiving rifampin for periods of 4 to 24 months. No significant changes were noted in lymphocyte responses to concanavalin A or pokeweed mitogen. In vitro and in vivo responses to purified protein derivative tuberculin were not altered. Because a favorable therapeutic outcome was achieved in all subjects, we concluded that rifampin does not have clinically significant immunosuppressive activity.

Animals↗
PubMed2006

Intranasal boosting with an adenovirus-vectored vaccine markedly enhances protection by parenteral Mycobacterium bovis BCG immunization against pulmonary tuberculosis.

Parenterally administered Mycobacterium bovis BCG vaccine confers only limited immune protection from pulmonary tuberculosis in humans. There is a need for developing effective boosting vaccination strategies. We examined a heterologous prime-boost regimen utilizing BCG as a prime vaccine and our recently described adenoviral vector expressing Ag85A (AdAg85A) as a boost vaccine. Since we recently demonstrated that a single intranasal but not intramuscular immunization with AdAg85A was able to induce potent protection from pulmonary Mycobacterium tuberculosis challenge in a mouse model, we compared the protective effects of parenteral and mucosal booster immunizations following subcutaneous BCG priming. Protection by BCG prime immunization was not effectively boosted by subcutaneous BCG or intramuscular AdAg85A. In contrast, protection by BCG priming was remarkably boosted by intranasal AdAg85A. Such enhanced protection by intranasal AdAg85A was correlated to the numbers of gamma interferon-positive CD4 and CD8 T cells residing in the airway lumen of the lung. Our study demonstrates that intranasal administration of AdAg85A represents an effective way to boost immune protection by parenteral BCG vaccination.

Acyltransferases↗
PubMed1994

Adhesion molecules mediating recruitment of monocytes to inflamed tissue.

Three families of cell-surface proteins are largely responsible for the adherence of leukocytes to cells and matrices: integrins, immunoglobulin (Ig)-related molecules and selectins. Blood monocytes express beta 1 integrins VLA-4, -5 and -6 and beta 2 integrins CD11a/CD18, CD11b/CD18 and CD11c/CD18. These cells also express the Ig-related molecules ICAM-1, -2 and -3, ligands for the beta 2 integrins. In addition, monocytes express L-selectin and the oligosaccharides Lex and sialyl Lex, ligands for the endothelial selectins E- and P-. In vitro studies with blocking antibodies have identified adhesion molecules participating in the adherence of monocytes to one another, to T lymphocytes and to vascular endothelial cells. These antibodies also block adhesion-dependent monocyte activities, such as cytotoxicity of tumor cells, antigen presentation, phagocytosis of large particles, induction of cytokine secretion, formation of multinucleated giant cells and HIV-induced syncytium formation. In vivo studies in animals have demonstrated participation of L-selectin and CD11b/CD18 in monocyte accumulation in inflamed peritoneum. Moreover, treatment with anti-CD11b antibodies potentiates primary listeriosis and inhibits the macrophage recruitment and granuloma formation, and anti-CD18 antibodies block ear swelling in Mycobacterium tuberculosis-immunized animals following challenge with PPD. Adhesion molecules may also play key roles in the pathogenesis of tuberculosis and AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Characterisation of target antigen of cell-mediated immunity in Mycobacterium tuberculosis H37RV.

Antigen participating in cell-mediated immunity was isolated from a sonic extract of Mycobacterium tuberculosis H37Rv. The purified antigen had a mol. wt 150 000-200 000, based upon its Rf in 7.5% polyacrylamide gel in the presence of sodium dodecyl sulphate. In simple agarose gel electrophoresis it had an Rf of 0.85. The protein in its native state was identified in the sonic extract with an antiserum to the purified antigen; it too had an Rf of 0.85 in agarose gel electrophoresis. The purified antigen elicited a delayed hypersensitivity response and stimulated the generation of activated macrophages in mice immunised with M. tuberculosis H37Rv.

Animals↗
PubMed2006

Recombinant M. smegmatis vaccine targeted delivering IL-12/GLS into macrophages can induce specific cellular immunity against M. tuberculosis in BALB/c mice.

In the present study, we constructed a viable therapeutic vaccine of recombinant M. smegmatis mediated IL-12/GLS (granulysin) gene transfer into murine macrophages to exert the immunotherapy effects on the Mycobacterium tuberculosis infection. We tested this recombinant therapeutic vaccine in an in vivo study to determine its capability of stimulating host specific immune responses against M. tuberculosis. BALB/c mice intranasally immunized with the therapeutic vaccine developed an efficient Th1 protective immune response against M. tuberculosis which was equal to that of the BCG strain. Inoculation intranasally with this viable vaccine induced high level of serum IFN-gamma, IL-12 and IgG2a. The viable vaccine was capable of inducing purified protein derivative (PPD) antigen-specific splenocytes proliferation and IFN-gamma production from T cells in spleens of the immunized mice. In addition, intranasally inoculation with the viable vaccine can induce PPD antigen-specific sIgA production in the broncho-alveolar lavage fluid (BALF) of the immunized mice. No change of IL-4 level was found in all groups. The therapeutic mechanism of this viable vaccine against M. tuberculosis infection observed here appeared to be a result of the specific Th1 immune response activated by mycobacterium antigen from M. smegmatis and the expression of sIL-12/GLS in alveolar macrophages via the M. smegmatis-mediated gene transfer method. This research demonstrates that the therapeutic gene can be introduced into a host by viable mycobacteria works to induce the host specific immune response against M. tuberculosis infection in vivo. Since this therapeutic vaccine can strongly induce specific Th1 responses against M. tuberculosis in BALB/c mice and has no obviously harmfulness to the host simultaneously, the recombinant vaccine might be a potential candidate therapeutic vaccine against tuberculosis.

Animals↗
PubMed2004

CD14 gene promoter polymorphism in different clinical forms of tuberculosis.

Mycobacterium tuberculosis interacts with monocyte-macrophages through cell surface molecules including CD14. A soluble form of CD14 (sCD14) exists in human serum, and higher amounts of it are found in tuberculosis. A polymorphism on CD14 gene promoter was associated with increased sCD14 levels in some diseases. To evaluate whether this polymorphism associates with tuberculosis, its clinical forms, and increased sCD14, genotype/allele frequencies in tuberculosis patients were compared with the controls. Results confirmed increased levels of sCD14 in patients with tuberculosis, and those with miliary tuberculosis had the highest levels. sCD14 decreased to normal levels after anti-tuberculosis treatment. No association was found between the CD14 polymorphism and tuberculosis or sCD14 levels. Results suggest that sCD14 may be involved in anti-tuberculosis immune response, but its increase is a consequence of infection rather than a predisposed genetic trait. Measuring sCD14 in tuberculosis may help monitor anti-tuberculosis treatment.

Adolescent↗
PubMed2003

Apoptosis facilitates antigen presentation to T lymphocytes through MHC-I and CD1 in tuberculosis.

Protective immunity against Mycobacterium tuberculosis involves major histocompatibility complex class I (MHC-I)- and CD1-restricted CD8 T cells, but the mechanisms underlying antigen delivery to antigen-presenting molecules remain enigmatic. Macrophages, the primary host cells for mycobacteria, are CD1-negative. Here we show that M. tuberculosis phagosomes are secluded from the cytosolic MHC-I processing pathway and that mycobacteria-infected cells lose their antigen-presenting capacity. We also show that mycobacteria induce apoptosis in macrophages, causing the release of apoptotic vesicles that carry mycobacterial antigens to uninfected antigen-presenting cells (APCs). Inhibition of apoptosis reduced transfer of antigens to bystander cells and activation of CD8 T cells. Uninfected dendritic cells, which engulfed extracellular vesicles, were indispensable for subsequent cross-presentation of antigens, through MHC-I and CD1b, to T cells from mycobacteria-sensitized donors. This new 'detour' pathway for presentation of antigens from a phagosome-contained pathogen shows the functional significance of infection-induced apoptosis in the activation of CD8 T cells specific for both protein and glycolipid antigens in tuberculosis.

Animals↗
PubMed1998

Human cytolytic and interferon gamma-secreting CD8+ T lymphocytes specific for Mycobacterium tuberculosis.

Protective immunity to Mycobacterium tuberculosis is poorly understood, but mounting evidence, at least in animal models, implicates major histocompatibility complex class I-restricted CD8+ T cells as an essential component. By using a highly sensitive assay for single cell interferon gamma release, we screened an array of M. tuberculosis antigen-derived peptides congruent with HLA class I allele-specific motifs. We identified CD8+ T cells specific for epitopes in the early secretory antigenic target 6 during active tuberculosis, after clinical recovery and in healthy contacts. Unrestimulated cells exhibited peptide-specific interferon gamma secretion, whereas lines or clones recognized endogenously processed antigen and showed cytolytic activity. These results provide direct evidence for the involvement of CD8+ cytotoxic T lymphocytes in host defense against M. tuberculosis in humans and support current attempts to generate protective cytotoxic T lymphocyte responses against M. tuberculosis by vaccination.

Adult↗
PubMed1981

Evans blue dye adjuvant enhances delayed hypersensitivity while blocking immunity to Mycobacterium tuberculosis in mice.

Evans blue dye functions as an adjuvant with protein antigens in saline to induce cell-mediated immunological responses in mice. But when used to help induce cell-mediated tuberculoimmunity, it decreased mouse resistance to tuberculosis instead of helping induce immunity. This paradox was investigated. As could be expected from previous work with other antigens, the dye did promote induction of delayed hypersensitivity in mice to tuberculoprotein when injected in saline with killed tubercle bacilli. Peritoneal macrophages from mice injected with the dye responded normally to migration inhibition factor. Morphologically, these cells were moderately "activated" compared with similar cells taken from untreated mice. However, such cells incubated with tuberculosis growth inhibition lymphokine in an in vitro test for tuberculoimmunity did not express tuberculoimmunity, whereas macrophages from untreated mice did. Therefore, Evans blue dye did promote induction of cell-mediated immunological responses and tuberculoimmunity in lymphocytes, but under the conditions used in these experiments, it also blocked expression of tuberculoimmunity by macrophages.

Adjuvants, Immunologic↗
PubMed1989

[Relation between malnutrition and cell-mediated immunity in pulmonary tuberculosis].

Although epidemiological studies have shown that malnutrition is associated with the reactivation and development of pulmonary tuberculosis, little is known about their nutritional status. We studied comprehensive profile of their nutritional status. We also studied the effects of malnutrition on cell-mediated immunity in tuberculosis patients. Nutritional status was assessed by anthropometric measurements and biochemical examinations, and cell-mediated immunity was evaluated by delayed-type hypersensitivity (DTH) reaction, lymphocyte transformation and natural killer (NK) activity in 47 patients with active pulmonary tuberculosis and 47 healthy controls. Cytokine production including IL-2, IL-1 was also examined. Anthropometrics and visceral proteins were significantly lower in tuberculosis patients. Fischer ratio (BCAA/AAA), an index of plasma amino acids imbalance, was significantly (p less than 0.01) lower in the patients. DTH to 2, 4-dinitrochlorobenzene and lymphocytes transformation were attenuated in the patients. NK activity was reduced in patients with severe pulmonary tuberculosis. The patient subgroup with reduced DTH was more malnourished than another one with normal DTH. The Fischer ratio correlated significantly with lymphocyte transformation response and visceral proteins and BCAA correlated with NK activity. IL-2 production was remarkably reduced in the patient subgroup whose serum albumin was less than 3.5 g/dl. IL-1 production was remarkably reduced in the patient subgroup whose serum albumin was less than 2.5 g/dl. Patient subgroup whose serum albumin level was more than 2.5 g/dl and less than 3.5 g/dl, produced remarkably more IL-1 than those whose serum albumin was more than 3.5 g/dl. These results suggested that malnutrition characterized by the reduction of the Fischer ratio was associated with impairment of cell-mediated immunity and cytokine production in pulmonary tuberculosis.

Humans↗
PubMed1979

Cost-benefit analysis of BCG-vaccination in Austria.

BCG-vaccination in Austria is performed generally in newborn, but only partially in school children. A cost-benefit analysis was performed considering age-dependent immunizations, tuberculosis morbidity, protection rate and duration of protection, costs of vaccination, costs of tuberculosis therapy, frequency of complications due to vaccination and costs for treatment of these complications. This analysis shows an economic balance between costs and benefits with regard to immunication of newborn, i. e., costs of vaccination are approximately compensated by the saved costs of prevented diseases. In contrary vaccination of school children reveals a considerable economic gain. General revaccination of schoolchildren would make BCG-vaccination much more effective in an economic respect.

Adolescent↗