Updated: 5/20/2017

Innate vs. Adaptive Immunity

Review Topic
Videos / Pods
  • Overview
  • Introduction
    • The human immune system is designed to deal with a variety of insults including
      • acute exposure to new infectious agents such as bacteria and viruses
      • re-exposure to the same infectious agent after clearance of the initial infection
      • chronic infection by fungi and parasites
    • In order to have a variety of responses to infection, the immune system is divided into
      • the innate immune system that is responsible for
        • fast recognization and clearance of initial infections
        • destruction of fungi and parasites
      • the adaptive immune system that is responsible for
        • immunological memory and rapid responses to re-infection
        • recognition of pathogens that have defences against innate immunity
  • Differences Between Innate and Adaptive Immunity
      • Differences Between Innate and Adaptive Immunity
      • Feature
      • Innate Immunity
      • Adaptive Immunity
      • Genetics
      • All components encoded in germline
      • May vary between individuals but does not change over course of an individual lifetime
      • Inherited from parents
      • Encoded as variable V, D, and J regions
      • Immunity is generated by recombination of these regions and further hypervariation
      • Not inherited from parents
      • Components
      • Myeloid lineage white blood cells such as
        • neutrophils
        • monocytes
        • macrophages
      • Natural killer (NK) cells
      • Complement system
      • Physical barriers (such as mucus membranes)
      • Killer CD8+ T-cells
      • Helper CD4+ T-cells
      • B-cells
      • Antibodies
      • Recognition
      • Uses receptors that recognize conserved pathogen-associated molecular patterns (PAMPs)
      • Examples linclude
        • LPS
        • flagellin
        • nucleic acids
      • Uses recombined B- and T-cell receptors that recognize specific antigens on pathogens
      • Can recognize aspects of almost all pathogens
      • Response
      • Nonspecific recognition
      • Occurs rapidly from minutes to hours
      • Does not confer memory
      • Specific recognition that can be refined
      • Occurs over days to years
      • Confirms immunological memory
      • Resistance
      • Caused by pathogenic virulence factors
      • Often involves disabling the conserved pattern recognition used by innate system
      • Caused by mutation of the recognized antigen
      • Can be overcome by further maturation of the receptor
  • Interactions between Innate and Adaptive systems
    • These two branches of the immune system can cooperate in several ways including
      • opsonization
        • coating pathogens with antibodies in order to activate
          • antibody dependent cellular cytotoxicity
          • antibody dependent cellular phagocytosis
      • complement activation
        • activation of the C3 convertase by the
          • classical complement pathway
          • interaction of antibodies with C1q
      • cytokine secretion
        • release of signaling molecules by helper T-cells causes
          • additional production of innate immune cells
          • synthesis of circulating factors such as the complement system
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