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Immunology

Immunology. Chapter 1 Dr. Capers IRSC. History. Discipline of immunology grew out of observation that individuals who recovered from infectious diseases were protected from disease 15 th Century Chinese and Turks tried to prevent smallpox

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Immunology

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  1. Immunology Chapter 1 Dr. Capers IRSC

  2. History • Discipline of immunology grew out of observation that individuals who recovered from infectious diseases were protected from disease • 15th Century • Chinese and Turks tried to prevent smallpox • Dried crust from pustules were inhaled or inserted into small cuts • 1718 • Lady Montagu had that technique done in her children

  3. History • 1798 • Edward Jenner • Noticed that milkmaids that contracted cowpox were immune to smallpox • Innoculated small boy with fluid from cowpox pustule • He then intentionally infected the boy with smallpox – the child did not develop smallpox • 1881 • Louis Pasteur • Vaccinated sheep with heat-attenuated anthrax • Then infected sheep with virulent strain of anthrax – they did not develop anthrax

  4. History • 1883 • Metchnikoff demonstrated that certain white blood cells were able to phagocytize microorganisms • 1901 • Von Behring and Kitasato • Demonstrated that serum (noncellular component of blood) from animals immunized to diptheria could transfer that immunity to non-immunized animals

  5. History • 1977 • Last known naturally acquired case of smallpox • Is it still a threat? • In industrialized nations, measles, mumps, whooping cough, tetanus, polio, and diptheria are extremely rare or nonexistent • This is due to vaccines! • Prevent death, paralysis, deafness, blindness, mental retardation

  6. A Little Bit of History

  7. Immune system evolved to protect multicellular organisms from pathogens • Does this by 2 related activites • Recognition and response

  8. Couple of terms we need to be familiar with: • Pathogen – something that causes disease • Antigen – any foreign substance that binds specifically to an antibody or T cell receptor • Immunogen – a substance capable of eliciting an immune response • All immunogens are antigens but not all antigens are immunogens (i.e. haptens) • Epitope – portion of the antigen that is recognized by an antibody or T cell receptor

  9. 2 Systems of Immunity • Innate Immunity • 1st line of defense • Molecular and cellular mechanisms deployed before an infection • Distinguishes between self and pathogens but not specialized to distinguish small differences in the foreign particles • Adaptive Immunity • Develops in response to infection • Adapts to recognize, eliminate, and remember pathogen

  10. Innate Immunity • Less specific • 1st line of defense • Barriers that protect host • Skin • Acidity of stomach • Lysozymes in fluids • Phagocytic cells • Antimicrobial peptides (interferons, complement) • Temperature

  11. Adaptive Immunity • Highly specific • Characteristic attributes • Antigenic specificity • Antibodies can distinguish between 2 proteins that differ in only 1 amino acid • Diversity • Immunologic memory • Self-nonself recognition

  12. Adaptive Immunity • Effective adaptive immune response involves 2 groups of cells • Lymphocytes • B cells • T cells • Antigen-presenting cells

  13. Adaptive Immunity - Lymphocytes • B cells • Mature in bone marrow • Antigen binding receptor – Antibody • Glycoproteins

  14. Adaptive Immunity - Antibodies • Glycoproteins • Structure • 2 identical polypeptides – heavy chains • 2 shorter identical polypeptides – light chains

  15. Antibodies • Antigen coated by antibody is eliminated in several ways • Antibody can cross-link several antigens, making it easier to be ingested by phagocytic cells • Activate complement system resulting in lysis of microorganism

  16. Adaptive Immunity - Lymphocytes • T cells • Arise in bone marrow but mature in thymus • 2 well define subpopulations of T cells • T helper cells • T cytotoxic cells

  17. T cells recognize antigen presented in MHC molecule • MHC = Major Histocompatibility Complex • MHC Class I – found on all of our nucleated cells • Cytotoxic T cells recognize this • MHC Class II – found on antigen presenting cells (B cells, dendritic cell and macrophages) • Helper T cells recognize this

  18. T cells • Cytokines secreted by TH cells can activate phagocytic cells • TC cells can kill altered self-cells • Cells infected by viruses • Tumor cells

  19. Antigen presenting cell associating with T cell

  20. Initial encounter with antigen causes primary response • Later contact with antigen will result in more rapid response – secondary response

  21. Immune Dysfunction • Allergies and Asthma • Graft rejection • Autoimmune Disease • Immunodeficiency

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