scholarly journals Specific Antibody to Cryptococcus neoformans Alters Human Leukocyte Cytokine Synthesis and Promotes T-Cell Proliferation

1998 ◽  
Vol 66 (3) ◽  
pp. 1244-1247 ◽  
Author(s):  
Anna Vecchiarelli ◽  
Cinzia Retini ◽  
Claudia Monari ◽  
Arturo Casadevall
Keyword(s):  
Cell Proliferation ◽  
T Cell ◽  
Cryptococcus Neoformans ◽  
Specific Antibody ◽  
Human Leukocyte ◽  
T Cell Proliferation ◽  
Cell Mediated Immunity ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Necrosis Factor

ABSTRACT Addition of a monoclonal antibody which binds theCryptococcus neoformans capsule to suspensions of human monocytes, T lymphocytes, and cryptococcal cells (i) enhances interleukin-1β (IL-1β), tumor necrosis factor alpha, and IL-2 production; (ii) reduces IL-10 secretion; and (iii) promotes T-cell proliferation. The ability of specific antibody to influence cytokine production and lymphoproliferation suggests a mechanism by which humoral immunity can influence cell-mediated immunity.

scholarly journals Phagocytosis and Protein Processing Are Required for Presentation of Cryptococcus neoformans Mitogen to T Lymphocytes

2000 ◽  
Vol 68 (11) ◽  
pp. 6147-6153 ◽  
Author(s):  
Rachel M. Syme ◽  
Jason C. L. Spurrell ◽  
Ling Ling Ma ◽  
Francis H. Y. Green ◽  
Christopher H. Mody
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cryptococcus Neoformans ◽  
T Cell Activation ◽  
Intracellular Transport ◽  
Cell Uptake ◽  
T Cell Proliferation ◽  
Accessory Cell ◽  
Cell Mediated Immunity

ABSTRACT In addition to eliciting antigen specific T-cell-mediated immunity,Cryptococcus neoformans possesses a mitogen (CnM) that activates naive T cells to proliferate. This mechanism of T-cell activation is accessory cell dependent and major histocompatibility complex unrestricted. CnM-induced T-cell proliferation correlates with internalization of the organism, suggesting that intracellular processing is required to liberate CnM prior to presentation to T cells. To determine whether phagocytosis and processing are required, various inhibitors of accessory cell uptake and processing were used.C. neoformans was observed within the accessory cells. Paraformaldehyde fixation of the accessory cell abrogated presentation of CnM to T cells, indicating that a dynamic accessory cell surface was required. A lysosomotropic agent abrogated the response to CnM but had no effect on a control stimulus that did not require processing. Both aspartic acid and cysteine protease inhibitors blocked effective processing of CnM, so that it was unable to stimulate T cells. Finally, an inhibitor of microfilament polymerization abrogated proliferation to CnM. These results indicate that the mitogenic activity of C. neoformans requires phagocytosis of the organism, lysosomal or endosomal processing, proteolytic activity, and microfilament polymerization and intracellular transport as a prerequisite for T-cell proliferation.

scholarly journals Cross-linking of CD4 molecules upregulates Fas antigen expression in lymphocytes by inducing interferon-gamma and tumor necrosis factor- alpha secretion

Blood ◽  
1994 ◽  
Vol 84 (8) ◽  
pp. 2622-2631 ◽  
Author(s):  
N Oyaizu ◽  
TW McCloskey ◽  
S Than ◽  
R Hu ◽  
VS Kalyanaraman ◽  
...  
Keyword(s):  
T Cell ◽  
Cell Apoptosis ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Cross Linking ◽  
Necrosis Factor Alpha ◽  
Ifn Gamma ◽  
T Cell Apoptosis ◽  
Factor Alpha ◽  
Necrosis Factor

Abstract We have recently shown that, in unfractioned peripheral blood mononuclear cells (PBMCs), the cross-linking of CD4 molecules (CD4XL) is sufficient to induce T-cell apoptosis. However, the underlying mechanism for the CD4XL-mediated T-cell apoptosis is largely unknown. Several recent studies have shown that Fas antigen (Ag), a cell-surface molecule, mediates apoptosis-triggering signals. We show here that cross-linking of CD4 molecules, induced either by anti-CD4 monoclonal antibody (MoAb) Leu3a or by human immunodeficiency virus-1 (HIV-1) envelope protein gp160, upregulates Fas Ag expression as well as Fas mRNA in normal lymphocytes. Addition of the tyrosine protein kinase inhibitor genistein or of the immunosuppressive agent cyclosporin A abrogated these effects. The upregulation of Fas Ag closely correlated with apoptotic cell death, as determined by flow cytometry. In addition, CD4XL resulted in the induction of interferon-gamma (IFN- gamma) and tumor necrosis factor-alpha (TNF-alpha) in the absence of interleukin-2 (IL-2) and IL-4 secretion in PBMCs. Both INF-gamma and TNF-alpha were found to contribute to Fas Ag upregulation and both anti- IFN-gamma and anti-TNF-alpha antibodies blocked CD4XL-induced Fas Ag upregulation and lymphocyte apoptosis. These findings strongly suggest that aberrant cytokine secretion induced by CD4XL and consequent upregulation of Fas Ag expression might play a critical role in triggering peripheral T-cell apoptosis and thereby contribute to HIV disease pathogenesis.

scholarly journals Targeting Mycobacterium tuberculosis Tumor Necrosis Factor Alpha-Downregulating Genes for the Development of Antituberculous Vaccines

mBio ◽  
2016 ◽  
Vol 7 (3) ◽  
Author(s):  
Aaron Olsen ◽  
Yong Chen ◽  
Qingzhou Ji ◽  
Guofeng Zhu ◽  
Aruna Dharshan De Silva ◽  
...  
Keyword(s):  
T Cell ◽  
Tumor Necrosis Factor ◽  
Host Cell ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Necrosis Factor Alpha ◽  
Cell Responses ◽  
Cell Immunity ◽  
Factor Alpha ◽  
Necrosis Factor

ABSTRACT Tumor necrosis factor alpha (TNF) plays a critical role in the control of Mycobacterium tuberculosis , in part by augmenting T cell responses through promoting macrophage phagolysosomal fusion (thereby optimizing CD4 + T cell immunity by enhancing antigen presentation) and apoptosis (a process that can lead to cross-priming of CD8 + T cells). M. tuberculosis can evade antituberculosis (anti-TB) immunity by inhibiting host cell TNF production via expression of specific mycobacterial components. We hypothesized that M. tuberculosis mutants with an increased capacity to induce host cell TNF production (TNF-enhancing mutants) and thus with enhanced immunogenicity can be useful for vaccine development. To identify mycobacterial genes that regulate host cell TNF production, we used a TNF reporter macrophage clone to screen an H37Rv M. tuberculosis cosmid library constructed in M. smegmatis . The screen has identified a set of TNF-downregulating mycobacterial genes that, when deleted in H37Rv, generate TNF-enhancing mutants. Analysis of mutants disrupted for a subset of TNF-downregulating genes, annotated to code for triacylglycerol synthases and fatty acyl-coenzyme A (acyl-CoA) synthetase, enzymes that concern lipid biosynthesis and metabolism, has revealed that these strains can promote macrophage phagolysosomal fusion and apoptosis better than wild-type (WT) bacilli. Immunization of mice with the TNF-enhancing M. tuberculosis mutants elicits CD4 + and CD8 + T cell responses that are superior to those engendered by WT H37Rv. The results suggest that TNF-upregulating M. tuberculosis genes can be targeted to enhance the immunogenicity of mycobacterial strains that can serve as the substrates for the development of novel anti-TB vaccines. IMPORTANCE One way to control tuberculosis (TB), which remains a major global public health burden, is by immunization with an effective vaccine. The efficacy of Mycobacterium bovis BCG, the only currently approved TB vaccine, is inconsistent. Tumor necrosis factor alpha (TNF) is a cytokine that plays an important role in controlling TB. M. tuberculosis , the causative agent of TB, can counter this TNF-based defense by decreasing host cell TNF production. This study identified M. tuberculosis genes that can mediate inhibition of TNF production by macrophage (an immune cell critical to the control of TB). We have knocked out a number of these genes to generate M. tuberculosis mutants that can enhance macrophage TNF production. Immunization with these mutants in mice triggered a T cell response stronger than that elicited by the parental bacillus. Since T cell immunity is pivotal in controlling M. tuberculosis , the TNF-enhancing mutants can be used to develop novel TB vaccines.

scholarly journals HLA-B*35-Restricted CD8+-T-Cell Epitope in Mycobacterium tuberculosis Rv2903c

2002 ◽  
Vol 70 (2) ◽  
pp. 981-984 ◽  
Author(s):  
Michèl R. Klein ◽  
Abdulrahman S. Hammond ◽  
Steve M. Smith ◽  
Assan Jaye ◽  
Pauline T. Lukey ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cell Epitope ◽  
T Cell Epitope ◽  
T Cell Epitopes ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Mycobacterial Antigens ◽  
Necrosis Factor

ABSTRACT Few human CD8+ T-cell epitopes in mycobacterial antigens have been described to date. Here we have identified a novel HLA-B*35-restricted CD8+ T-cell epitope in Mycobacterium tuberculosis Rv2903c based on a reverse immunogenetics approach. Peptide-specific CD8 T cells were able to kill M. tuberculosis-infected macrophages and produce gamma interferon and tumor necrosis factor alpha.

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