Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reactional leprosy is studied according to its clinical forms A) Lepromatous a) Acute lepromatization: encroaching and invasive nature; the patient becomes more and more lepromatous ; bad prognosis. b) Erythema nodosum: "contusiform dermatitis"; variable prognosis not so bad as it is in the preceding case; allergic nature and its evolution is usually detained and therapeutics efficient. c) Erythema multiform. d) Lucio's phenomenon: vascular lesions and consequently necrosis as a complication of the "erythema necrotisans" (beautiful leprosy). B) Tuberculoid Reactional tuberculoid is the only one in this benign type, the Mitsuda's test must always be positive and prognosis consequently good. C) Dimorphous or "Borderline" whose Mitsuda's test is mostly negative, sometimes positive, but not stable. The lesions may stimulate the tuberculoid leprids but they invade mucous membranes, are impregnated by pigmentation, may present the Unna's band, and other characteristics of the Lepromatous type. Are associated (fever, asthenia and emaciation). Prognosis not very good, because of the possibility of lepromatization, according to its tendency. Evolution slower and frequent relapses. Besides there are nodular lesions. Pathogeny 1) Perifocal allergic reaction (Jadassohn). Similar to epituberculosis and Herxheimer reaction. 2) Septicemia. Sensitized tissues inside or outside the lesions, are invaded by the bacilli and so the allergic reaction takes place. Even without culture resources, Mycobacterium leprae has been found in the blood by direct examination. 3) Autoimmunization (Waldenstrom, Matthews and Trantman, 1965). Based upon the similarity between both humoral syndromes, in leprosy reactions and collagenous, diseases, as to: hypergammaglobulins, hypercryoproteins, antigammaglobulins, serological reactions (Wassermann, Kahn, Kline, VDRL) positives, Antistreptolysin O, protein C reactive, antinuclear factors, latex and Wadler-Rose test positives (rheumatoid tests) lowering of complement. If leprosy reaction is like this, it should be the less agressive of the autoimmune diseases. a) Its eruptions are cyclic not of long standing duration, as a general rule. b) Its prognosis has been recognized as good, except lately, because of the use of corticoid therapy which has been fatal, in many cases. After some years the leprosy reaction cures spontaneously. Treatment (see article)
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PMID:[Reactional status of leprosy]. 124 Oct 72

NK cell clones obtained from three different donors were tested for their ability to present soluble proteins to Ag-specific T cell clones. All NK clones were CD2+CD3-CD56+, whereas the expression of CD16 varied from clone to clone. The NK cell clones were able to process and present tetanus toxoid (TT) to TT-specific T cell clones in a class II HLA restricted manner. The capacity of NK cell clones to function as APC was also observed using the house dust mite allergen Der p I and the Der p I-derived peptide Val89-Cys117. As with EBV-transformed B cell line, NK cell clones could present the peptide 3-13 derived from the 65-kDa heat shock protein of Mycobacterium leprae, but they were unable to present the whole M. leprae Ag. Freshly isolated NK cells, IL-2-activated NK cells, and NK cell lines expanded in vitro could also process and present TT. The ability of the different NK populations to act as accessory cells correlated with their levels of class II HLA expression. These data demonstrate that NK cell clones can efficiently function as APC, however they may be restricted in the types of Ag that they can process.
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PMID:Natural killer cell clones can efficiently process and present protein antigens. 186 Oct 74

Protection against infection with Mycobacterium tuberculosis is preferentially associated with the development of the T helper 1 subset, IFN-gamma production and a cell-mediated response, rather than with T helper 2 cells, 4 (IL-4) and antibody production. The type of APC interacting with T cells responsive to mycobacterial peptides may influence which of these responses predominates. This investigation focuses on the role of dendritic cells (DC) because they are the most potent APC in both primary and recall immune responses. Our results show that splenic DC-enriched suspensions prepared from C57BL/6 mice and pulsed with either purified protein derivative (PPD) or the immunodominant 19 kDa protein from M. tuberculosis, can activate antigen-primed T cells in vitro, whereas spleen cell suspensions depleted of DC cannot. DC pulsed with PPD or 19 kDa antigen are able to prime naive T cells in vivo. Supernatants collected from cultures containing T cells from mice injected with PPD-pulsed DC and then challenged in vitro with PPD-pulsed DC were found to contain more IL-2 and IFN-gamma than those from control mice which received either DC or PPD alone. No such antigen-specific IFN-gamma response occurred if DC pulsed with 19 kDa were used in place of PPD-pulsed DC. IL-4 was not detected in any of the culture supernatants. We conclude that DC can induce production of cytokines associated with a protective immune response when presenting peptides derived from heterogeneous mycobacterial antigens but not when exposed to the single 19 kDa immunodominant protein.
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PMID:Dendritic cell presentation of PPD and 19 kDa protein of Mycobacterium tuberculosis and emergent T helper cell phenotype. 871 75

Peripheral blood V gamma 9/V delta 2 T cells proliferate vigorously in response to heat-killed Mycobacterium tuberculosis (Mtb) and Daudi Burkitt's lymphoma cells. We have analyzed the respective roles of IL-10 and IL-12 in gamma delta T cell activation, using the selective expansion of V gamma 9 cells in Mtb- or Daudi-stimulated PBMC as a readout. IL-10 inhibited in a dose-dependent fashion the V gamma 9 responsiveness to Mtb. In contrast, IL-10 did not impair reactivity toward Daudi cells, even when added at 10 ng/ml. The inhibitory action of IL-10 could be overcome by the exogenous supply of IL-2 or IL-12. Blockade of endogenous IL-10 by neutralizing mAb increased responsiveness to Mtb but not to Daudi cells. Low concentrations of exogenous IL-12 increased the V gamma 9 responsiveness to Mtb in 6 of 11 healthy donors. In contrast, IL-12 inhibited V gamma 9 cell expansion in response to Daudi stimulation in all of the tested individuals. Neutralizing anti-IL-12 Ab significantly suppressed V gamma 9 responsiveness to Mtb in IL-12 nonresponders but only slightly inhibited the latter responsiveness in IL-12 responders. The effect of anti-IL-12 Ab correlated with the level of Mtb-stimulated endogenous IL-12 production. In purified gamma delta T cells, IL-12 synergized with IL-2 to stimulate cellular expansion in response to Daudi cells. This effect was reduced when T cell-depleted APC were added back. Finally, neutralization of endogenous IFN-gamma by Ab abrogated V gamma 9 cell responsiveness to Mtb but exerted only a minor inhibition of the reactivity toward Daudi cells. Taken together, these results reveal significant differences in the cytokine requirement of gamma delta T cell activation by Mtb or Daudi lymphoma cells, respectively.
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PMID:Activation of human gamma delta T cells by Mycobacterium tuberculosis and Daudi lymphoma cells: differential regulatory effect of IL-10 and IL-12. 905 20

Dendritic cells (DC) play an essential role in the initiation of primary T cell responses to foreign Ag. It is likely that these potent APC are critical in the initiation of immune responses to pathogens, such as bacteria or parasites. However, little is known about the interaction of these important APC with pathogens. To address this issue, the interaction of the bacterium Mycobacterium tuberculosis with human DC was studied. DC generated from human peripheral blood by short term culture in medium containing recombinant human cytokines granulocyte-macrophage-CSF and IL-4 were capable of phagocytosing M. tuberculosis. Infection of DC with live M. tuberculosis bacilli resulted in increased APC surface expression of the costimulatory molecules CD54, CD40, and B7.1, as well as MHC class I molecules. In addition, infected DC secreted elevated levels of inflammatory cytokines, including TNF-alpha, IL-1, and IL-12. M. tuberculosis-infected human monocytes also secreted inflammatory cytokines, but exhibited no enhancement of costimulatory or MHC class I molecule expression. These data indicate that infection with M. tuberculosis results in the direct activation and maturation of these DC. In vivo, such activation may facilitate migration to the lymph nodes, and enhance presentation of Ag to T cells, thereby facilitating the induction of the immune response against this pathogen.
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PMID:Activation of human dendritic cells following infection with Mycobacterium tuberculosis. 921 78

IL-12 secretion by APC is critical for the development of protective Th1-type responses in mycobacterial (Mycobacterium avium and Mycobacterium tuberculosis) infections in mice. We have studied the role of IL-12 and IL-2 in the generation of Mycobacterium leprae-specific T cell responses in humans. Leprosy patients were defined as low/nonresponders or high responders based on the level of T cell proliferation in M. leprae-stimulated PBMC. In high responders, M. leprae-induced proliferation was markedly suppressed by neutralizing anti-IL-12 mAb (inhibition 55 +/- 6%). Neutralization of IL-2 activity resulted in an inhibition of 77 +/- 4%. Given the importance of endogenous IL-2 and IL-12 in M. leprae-induced responses, we investigated the ability of rIL-2 and rIL-12 to reverse T cell unresponsiveness in low/nonresponder patients. Interestingly, rIL-12 and rIL-2 strongly synergized in restoring both M. leprae-specific T cell proliferation and IFN-gamma secretion almost completely to the level of responder patients. A similar synergy between rIL-2 and rIL-12 was also observed in high responders when suboptimal M. leprae concentrations were used for T cell stimulation. Our data demonstrate a crucial role for endogenous IL-12 and IL-2 in M. leprae-induced T cell activation. Most importantly, we show that rIL-2 and rIL-12 act in synergy to overcome Ag-specific Th1 cell unresponsiveness. These findings may be applicable to the design of antimicrobial and antitumor vaccines.
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PMID:IL-2 and IL-12 act in synergy to overcome antigen-specific T cell unresponsiveness in mycobacterial disease. 921 96

Both experimental and clinical forms of chronic GVHD have unique immunological features. The affected animals/individuals suffer from autoimmune disorders such as systemic lupus erythematosus (SLE), and yet they are unable to mount a self MHC-restricted T cell response to foreign antigens. Pathogenesis of the latter phenomenon was investigated in an experimental model of chronic GVHD. Chronic GVHD was induced in 8-10-week-old (B6xC3H)F1 mice by tail vein injection of 5 x 10(7) spleen cells of C3H parental strain. The recipients, when tested 3 months later, were unable to mount a T helper (Th) cell response to a randomly selected immunogen, a vaccine of l0(8) killed Mycobacterium vaccae. The animals showed evidence of generalized lymphoid hyperplasia, as indicated by GVH index >1.34, and also revealed autoantibodies against erythrocytes and dsDNA, indicating establishment of chronic GVHD. However, mice with chronic GVHD of only 3 weeks duration were able to mount the Th cell response to M. vaccae. Three consecutive immunizations of these mice at 1-week intervals, with the same immunogen, resulted in the mice becoming non-responsive to the antigen. All the three responses tested, namely the DTH, lymphoproliferation and the antibody responses, were adversely affected. The non-responsiveness induced was antigen-specific. Mice receiving two immunizations with M. vaccae responded normally to Salmonella enteritidis. Pulse treatment with cyclosporin A 0.5 mg/mouse by the i.p. route, on days 0, 1, 2, 3 and 4 at the time of immunization with M. vaccae on day 1, prevented emergence of non-responsiveness. Based on this evidence, it was concluded that repeated activation of T cells of mice with chronic GVHD induces non-responsiveness. Extent of clonal loss due to activation-induced cell death (AICD) caused by i.p. injection with a superantigen Staphylococcal enterotoxin B (SEB) was investigated in F1 mice with chronic GVHD. I.p. injection of 25 microg/mouse of SEB induced loss of SEB responding clones in both normal F1 mice and those having chronic GVHD; however, the extent of loss was much greater in the latter. In vitro antigen-specific proliferation of primed splenic T cells of normal F1 mice was observed to be quite poor when antigen was presented by APC of mice with chronic GVHD of 3 weeks duration. Proliferation profiles of T cells of normal F1 mice, in response to stimulation with concanavalin A (Con A) or SEB, were studied, using as APC irradiated spleen cells of normal F1 mice or of F1 mice with chronic GVHD of 3 weeks duration. With Con A and APC of normal F1 mice, peak proliferation was observed at 48 h, which remained at the same level up to 72 h and declined thereafter, possibly due to AICD. With SEB and the normal APC, proliferation progressively peaked at 72 h and declined thereafter. With APC of mice with chronic GVHD, the 48 h proliferative responses of both Con A and SEB were comparable to those caused by APC of normal F1 mice; however, thereafter the responses declined steeply, suggesting greater AICD. Based on these results, it was concluded that APC of mice with chronic GVHD are functionally altered to induce greater AICD.
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PMID:Antigen-presenting cells (APC) of mice with chronic graft-versus-host disease (GVHD) cause excessive activation-induced death of T helper cells. 940 51

Intracellular pathogens have developed efficient evasion strategies to survive the defenses of the host immune system. In this study, we describe a new escape mechanism utilized by Mycobacterium tuberculosis that involves the down-regulation of the Ag-presenting molecule CD1 from the cell surface of CD1+ APCs. The loss of CD1 from the cell surface is associated with a complete inhibition of the ability of the infected cells to present Ag to CD1-restricted T cells. The down-regulation of Ag-presenting molecules on CD1+ APC by infection with M. tuberculosis is unique for CD1, since the expression of the classical Ag-presenting molecules MHC class I and MHC class II is not influenced. Our data show that efficient down-regulation of CD1 requires infection of the cells with live mycobacteria, since heat killing of the bacteria completely abrogates the effect. The observed down-regulation is not due to the secretion of cytokines or other host- or pathogen-derived factors. Investigation of upstream events responsible for the down-regulation of CD1 revealed that infection with live M. tuberculosis decreased the steady state CD1-mRNA levels. This study introduces a novel evasion mechanism of M. tuberculosis that could contribute to persistence of intracellular infection by avoiding immune recognition.
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PMID:Down-regulation of CD1 on antigen-presenting cells by infection with Mycobacterium tuberculosis. 975 80

Studies suggested that experimental autoimmune diseases can effectively be prevented and treated by application of normal autoreactive T cells or autoreactive T cells in an attenuated form. In this study, several autoreactive CD4- CD8- T-cell clones (A2, A6, and A13 cells) were isolated for the first time from the draining lymph nodes of Lewis rats with adjuvant arthritis (AA). Surprisingly, intraperitoneal inoculation with A13 cells, but not A2 or A6 cells protected rats from AA both clinically and histologically. It was demonstrated that A13 cells were CD4- CD8- alpha beta T cells, and showed proliferative responses to irradiated syngeneic spleen cells (antigen-presenting cells; APC). Interestingly, A13 cells proliferated against concanavalin A (Con A) and staphylococcal enterotoxin B (SEB), but did not show any proliferation to Mycobacterium tuberculosis (Mt), or its 65 000 MW heat-shock protein (HSP). Rats protected from AA by inoculation with A13 cells showed a specific anti-idiotypic delayed-type hypersensitivity reaction compared with other autoreactive T cells (A2 or A6 cells). These findings demonstrate that AA can be suppressed by autoreactive CD4- CD8- alpha beta T cells, and these cells may be used as therapeutic agents in experimental autoimmunity.
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PMID:Autoreactive CD4- CD8- alpha beta T cells to vaccinate adjuvant arthritis. 976 42

The interaction of CD40 ligand (CD40L) expressed by activated T cells with CD40 on macrophages has been shown to be a potent stimulus for the production of IL-12, an obligate signal for generation of Th1 cytokine responses. The expression and interaction of CD40 and CD40L were investigated in human infectious disease using leprosy as a model. CD40 and CD40L mRNA and surface protein expression were predominant in skin lesions of resistant tuberculoid patients compared with the highly susceptible lepromatous group. IL-12 release from PBMC of tuberculoid patients stimulated with Mycobacterium leprae was partially inhibited by mAbs to CD40 or CD40L, correlating with Ag-induced up-regulation of CD40L on T cells. Cognate recognition of M. leprae Ag by a T cell clone derived from a tuberculoid lesion in the context of monocyte APC resulted in CD40L-CD40-dependent production of IL-12. In contrast, M. leprae-induced IL-12 production by PBMC from lepromatous patients was not dependent on CD40L-CD40 ligation, nor was CD40L up-regulated by M. leprae. Furthermore, IL-10, a cytokine predominant in lepromatous lesions, blocked the IFN-gamma up-regulation of CD40 on monocytes. These data suggest that T cell activation in situ by M. leprae in tuberculoid leprosy leads to local up-regulation of CD40L, which stimulates CD40-dependent induction of IL-12 in monocytes. The CD40-CD40L interaction, which is not evident in lepromatous leprosy, probably participates in the cell-mediated immune response to microbial pathogens.
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PMID:A role for CD40-CD40 ligand interactions in the generation of type 1 cytokine responses in human leprosy. 1090 57


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