chapter_2 - Chapter 2: Innate Immunity Innate immunity is...

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Innate immunity is germline encode (you are born with it ready to go) It has made the self/nonself discrimination on an evolutionary time-scale It uses few receptors that recognize molecular patterns common to many microorganisms Therefore, parts of it are always active or can be activated quickly Innate immunity is the first line of defense . Without innate immunity nearly every microorganism would be pathogenic Chapter 2: Innate Immunity
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Innate too No memory The response to an infection occurs in three phases: innate immunity early induced innate immunity adaptive immunity and memory cells
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Where to you find pathogens ? (CTL) (T H 1)
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How do pathogens damage tissues? These are caused by the immune response, not by the pathogen bacteria bacteria viruses
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Most surface epithelia are constantly exposed to microorganisms. Many microorganisms grow on these surfaces (e.g., skin, gut) or must cross an epithelial barrier (skin, gut, respiratory) to enter the body.
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Mucus prevents attachment; tears, saliva wash away microorganisms (prevent adherence) phagocytes = neutrophils and macrophages Skin provides a physical/chemical barrier to invasion (thick, tough, dry, acidic, toxic) inflammation Lots of macrophages in the liver, lungs, spleen and near epithelial surfaces Stages of an infection To lymph node i.e., antibody, T H 1, CTL
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Epithelial barriers to pathogens
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Also, macrophages may release toxic molecules including reactive oxygen species, nitric oxide and other (see figure 2.9) Macrophages release cytokines to affect other cells (e.g., endothelial cells) and cause inflammation. Cytokines from non- macrophages may activate macrophage, dendritic cells and cause inflammation Toll-like receptor (TLR) Macrophages are activated by pathogens. They kill pathogens and initiate inflammation
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Anti-bacterial agents produced by phagocytes (macrophages and/or neutrophils) upon bacterial stimulation [Reactive oxygen species (ROS)]
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Inflammation Inflammation is induced when macrophages bind bacterial products (e.g., LPS, peptidoglycan) (lots of other causes of inflammation): 1. Delivers effector cells and molecules to the site of the infection and augments macrophages that are already there 2. Creates a barrier to the spread of the microorganisms (captures microorganisms, blood clot prevents microorganisms from entering the circulation) 3. Repairs the damage What is the cause of the heat, redness, swelling and pain associated with inflammation?
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The macrophages’ affects on endothelial cells (the cells that line the blood vessels and largely control inflammation by controlling the flow of cells and fluids out of the post-capillary venules) result from release of prostaglandins, leukotrienes and cytokines such as IL-1, IL-8 and tumor necrosis factor- α ( TNF ). Blood coagulation stops bleeding and prevents pathogens from
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chapter_2 - Chapter 2: Innate Immunity Innate immunity is...

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