Innate immunity
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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

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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


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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


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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


Innate immunity

  • 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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