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Innate Immunity. Present before exposure to pathogens Present at birth Non-antigen specific Consists of: Skin… barrier for microbes and viruses Compromised by abrasion or laceration Sebacious sweat is acidic (pH 3-5)… prevents colonization of bacteria

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innate immunity
Innate Immunity
  • Present before exposure to pathogens
  • Present at birth
  • Non-antigen specific
  • Consists of:
    • Skin… barrier for microbes and viruses
      • Compromised by abrasion or laceration
      • Sebacious sweat is acidic (pH 3-5)… prevents colonization of bacteria
    • Mucus membranes… secrete mucus to trap microbes
      • Mucocilliary escalator moves trapped microbes out of the trachea
      • Secretions contain lysozyme, an enzyme, to digest the walls of bacteria
innate immunity1
Innate Immunity
  • Phagocytic cells
    • Mediate inflammation to limit the spread of microbes
    • Contain antimicrobial proteins that bind to the surface of bacteria
    • Once engulfed the phagocyte fuses a lysosome to the vacuole containing the bacteria
    • Some bacteria evade phagocytes by hiding surface recognition via a capsule
    • Types:
      • Neutorphils… 60-70% of all WBCs
        • Attracted to infection
        • Sacrifice themselves after phagocytosis
      • Macrophages… ~5% (developed from monocytes)
        • Attack microbes trapped in the lymph system and various other organs
      • Eosinophils… active against multicellular invaders
        • Inject enzymes to damage organism
      • Dendritic cells… stimulate acquired immunity after ingestion of cells
innate immunity2
Innate Immunity
  • The compliment system consists of over 30 proteins that when activated attack organisms and activate the immune system
    • Initiated be lysozyme
    • Interferon… limits viral replication in cells neighboring an infected cell
      • Non-specific
  • Inflammatory response… due to injury of pathogens
    • Created by histamine release from mast cells in the epithelium
      • Cause swelling of capillaries and increased blood flow that leaks fluid into tissues bringing macrophages
        • Discharge of prostaglandins that further promotes blood flow
        • Release chemokines that direct phagocytes to the infected area
innate immunity3
Innate Immunity
  • Natural Killer Cells
    • Patrol the body looking for infected cells.
      • They attack and cause cell death through apoptosis
      • Evaded in some viral infections and cancer
acquired immunity
Acquired Immunity
  • Often called adaptive immunity
  • Developed only after exposure
  • Highly specific
slide6

Lymphocytes… key cells in acquired immunity

    • Activated by the presence of cytokines
    • Antigens (foreign particles) elicit the immune response
      • Epitote… small part of the antigen molecule that is recognized by a specific lymphocyte
        • Each lymphocyte may contain up to 100,000 identical epitote recognition sites
      • Activation causes immediate clonal response producing 2 additional cells… 1 being a memory cell
        • Called the primary immune response
          • Maximum response 10-17 days after initial exposure
            • Sickness ensues awaiting max immune response
acquired immunity1
Acquired Immunity
  • B-lymphocytes… recognize and bind to intact surface antigens
    • Developed in the bone marrow from pluripotent cells
    • Secrete antibodies
        • Bind to antigens to mark for elimination
        • Shorten subsequent infections
          • Called the secondary immune response
acquired immunity2
Acquired Immunity
  • T-lymphocytes… similar to B-lymphocytes but can bind to smaller epitotes called MCH molecules
    • Originate in the bone marrow but mature in the thymus gland
    • Class 1 MCH… found on almost every cell in the body
      • Are presented when the cell becomes infected signaling the cytotoxic (killer) T-cells
    • Class 2 MCH… presented by macrophages, dendritic cells, and B-cells through antigen-presenting.
      • Signals the helper T-cells
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