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| − | =Introduction= | + | {{frontpage |
| | + | |pagetitle =Innate Immune System |
| | + | |pagebody = Both the innate and adaptive immune systems use receptors to recognise foreign organisms. The innate immune system uses pattern recognition receptors which acts as an early warning system. The adaptive immune response is highly specific for each organism, as B and T cells have specialist surface immunoglobulin receptors which detect specific antigens on foreign pathogens. |
| | + | <br>The Innate immune system is the body's first barrier of defence to infection. It relies on an older, more generic, and faster acting set of tools than the [[:Category:Adaptive Immune System|adaptive]] system. While the adaptive system is essential for a specific response to infection, it is ultimately the innate system that conquers foreign attackers through means of phagocytosis. |
| | + | |contenttitle = Content |
| | + | |contentbody =<big><b> |
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| − | The Innate immune system is the body's first barrier of defence to infection. It relies on an older, more generic, and faster acting set of tools than the [[Adaptive Immune System - WikiBlood|adaptive]] system. While the adaptive system is essential for a specific response to infection, it is ultimately the innate system that conquers foreign attackers through means of phagocytosis.
| + | <categorytree mode=pages>Innate Immune System</categorytree> |
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| − | * Non-specific protective mechanisms include such innate factors as:
| + | </b></big> |
| − | ** '''Physical barriers'''
| + | |logo = Immature MDDC.png |
| − | *** Skin
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| − | *** Ciliated mucous membranes
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| − | *** Commensal organisms
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| − | ** '''Humoral factors'''
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| − | *** Lysozyme
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| − | *** [[Complement|Complement]]
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| − | *** Interferons
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| − | ** '''Cellular mechanisms'''
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| − | *** Phagocytosis
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| − | ** Factors which regulate '''species specificity'''
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| − | *** Membrane receptors for pathogens
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| − | *** Nutritional requirements
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| − | *** Temperature
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| − | *** pH
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| − | * Mechanisms of innate immunity are always present and generally unchanging
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| − | * Adaptive immunity is acquired only on contact with the infectious agent (antigen) and therefore does not function before first contact with the antigen
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| − | =Actions of the Innate Immune System=
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| − | ==[[Recognition of Microorganisms]]==
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| − | ==[[Phagocytosis]]==
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| − | =Tools of Innate Immunity=
| + | [[Category:Immunology|B]] |
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| − | ==[[Innate Immunity Barriers]]==
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| − | ==[[Humoral Factors of Innate Immune System]]==
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| − | ==[[Innate Immunity Cellular Responses]]==
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| − | =Innate Immunity to Viruses=
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| − | [[Image:Innate viral response.jpg|thumb|right|150px|Innate response to dsRNA - B. Catchpole, RVC 2008]]
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| − | Because viruses invade host cells to take over a host's cellular machinery, the innate system has a more difficult time detecting viruses as foreign agents. However, there is a give-away element of the viral attack that the innate system can recognize: the '''double-stranded RNA''' (dsRNA) produced by a virus in its replication phase. Because mammalian cells only ever produce single-stranded RNA, the presence of dsRNA signals a foreign intruder. dsRNA can be detected by TLR-3R on the cell surface or intracellularly by the presence of dsRNA-dependent protein kinase.
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| − | The innate response to viral attack also depends on the presence of '''Type-1 Interferons''', which are produced by all cells on recognition of a viral attack. Interferons serve to increase degradation of mRNA, inhibit protein synthesis, and increase the effectiveness of the adaptive response by increasing antigen presentation to antibody.
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| − | Lastly, the final line of defense for the innate response to viruses lies in the actions of [[Lymphocytes#Natural Killer (NK) Cells|'''Natural Killer (NK) cells''']]. These warriors monitor the production of [[MHC - WikiBlood|MHC]] (Major Histocompatibility Complex) on the surface of cells, which is produced as part of the adaptive response. A cell whose cellular machinery is compromised by viral infection will experience a drop in the amount of MHC it produces. When a cell's MHC production drops, NK cells are triggered to phagocytose these cells. As such, this is a non-specific targeting based simply on the ability of a cell to function normally, which also lends them to playing a role in targeting malignant cells. NK cells are incapable of directly targeting viral infection.
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| − | =Innate Immunity to Bacteria=
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| − | [[Image:Bacterial innate response.jpg|thumb|right|150px|Bacterial responses - B. Catchpole, RVC 2008]]
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| − | The innate response to bacterial infection lies in its first-response role of detection of a foreign organism. By using the above described tools of Pattern-Recognition Receptors (PRRs), the innate response flags up problems while the [[Adaptive Immune System - WikiBlood|adaptive]] response gets itself organized. Once a foreign organism is detected, the innate system responds by engaging in cell warfare via phagocytosis and triggering the [[Inflammation - WikiBlood|inflammatory]] response. The release of inflammatory [[Cytokines - WikiBlood|cytokines]] will cause an increase in vasodilation, vascular permeability and an influx of white blood cells. Neutrophils take on their primary role as phagocytes in this phase. In addition, systemic effects of inflammatory cytokines will sustain a rise in core temperature (fever), the release of acute phase proteins from the [[Liver - Anatomy & Physiology|liver]], and bone marrow mobilization as the need for white blood cells production is increased. Acute phase proteins will bind to bacterial cell walls, enhancing neutrophil, macrophage, and [[Complement|complement]]-initiated phagocytosis.
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| − | =[[Interplay of Innate and Adaptive Immunity - WikiBlood|Interplay of Innate and Adaptive Immunity]]=
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| − | =[[Innate Immunity Flashcards|Innate Immunity Flashcards]]=
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| − | =Links=
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| − | '''Websites'''
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| − | *http://www.cellsalive.com
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| − | =References=
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| − | [[Category:Immunology]]
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