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Published byLuke Wilkinson Modified over 9 years ago
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Maja Marković, 2nd year, 2013/2014 Mentor: A. Žmegač Horvat
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Antigen word origin: antibody generator / anti(body)-gen = any substance foreign to the body that evokes an immune response parts of bacteria, viruses, parasites, foods, venoms, blood components, and cells and tissues of various species, including other humans
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epitope - a molecular region on the surface of an antigen capable of eliciting an immune response and combining with a specific antibody
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antigen ≠ immunogen hapten - a small molecule that can elicit an immune response only when attached to a large carrier such as a protein urushiol → quinone (reacts with skin proteins) hydralazine (blood pressure-lowering drug) → drug-induced lupus erythematosus halothane (anesthetic gas) → hepatitis penicillin-class drugs → autoimmune hemolytic anemia
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allergens = antigens which produce an abnormally vigorous immune response to a perceived threat that would otherwise be harmless to the body
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superantigens (SAg) produced by pathogenic microbes as a defense mechanism against the immune system cause non-specific activation of T-cells → polyclonal T cell activation and massive cytokine release (interferon gamma → macrophages → proinflammarory cytokines IL-1, IL-6, TNF-alpha) antigen-induced T-cell response: 0.0001 - 0.001% → 25 % shock and multiple organ failure
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tumor antigens presented by MHC I or MHC II molecules on the surface of tumor cells tumor-specific antigens (TSAs) - presented only by tumor cells tumor-associated antigens (TAAs) - presented by tumor cells and normal cells cytotoxic T lymphocytes may be able to destroy tumor cells before they proliferate, B-cells recognize mutated cell receptors used as tumor markers (alphafetoprotein, carcinoembryonic antigen CA-125, MUC-1, epithelial tumor antigen ) and vaccines
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Antibodies large glycoproteins, part of the immunoglobulin superfamily produced by plasma cells soluble or membrane-bound basic structure: "Y"-shaped molecule two identical heavy chains (α, ε, γ, δ, and μ, define the class) two identical light chains (λ and κ) connected by disulfide bonds constant and variable regions
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Fab region - antigen-binding paratope - at the amino terminal end of the antibody, variable domains from the heavy and light chains F V region, variable loops of β-strands, three each on V L and V H Fc region - ensures that each antibody generates an appropriate immune response for a given antigen (recognition of opsonized particles, lysis of cells, and degranulation of mast cells, basophils and eosinophils)
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more than 350 types of molecules markers on the cell surface critical in antigen recognition (CD4, CD8) cell surface receptors for growth factors (CD135)
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MHC molecules = major histocompatibility complex (human leukocyte antigen, HLA) a set of cel-surface molecules encoded by a large gene family in all vertebrates MHC-I: all nucleated cells; cytotoxic T lymphocyte MHC-II: dendritic cells, mononuclear phagocytes, B lymphocytes, some endothelial cells, epithelium of thymus; helper T lymphocytes
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MHC determines compatibility of donors for organ transplant and one's susceptibility to an autoimmune disease via crossreacting immunization
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Sources Taradi, Milan: Imunologija, 7. dopunjeno izdanje, 2010. http://www.merriam-webster.com/ http://en.wikipedia.org/wiki/Antigen http://en.wikipedia.org/wiki/Antibody
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