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Dr. Fang-Ping Huang Department of Pathology,

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  • 1. Dr. Fang-Ping Huang Department of Pathology, Immunology Division, Room 216 Tel. 2855 4864 Email: fphuang@hkucc.hku.hk
  • 2.
    • The immune system - an overview (basic concepts, features)
    • Developmental biology of the immune system (Dr. L. Lu)
    • Recent advances in lymphocyte lineage commitment (Dr. L. Lu)
    • Apoptosis & the molecular cell death pathways (Dr. L. Lu)
    • Antigen recognition by T cells & its MHC restrictions
    • Pathways of antigen processing, presentation & co-stimulations
    • Dendritic cells & the initiation of immune responses
    • Immune regulation & dys-regulation in health & in diseases
    Essence and Advances in Contemporary Immunobiology
  • 3.
    • Basic concepts in immunology
    • Vaccination & the history of immunology
    • Types of immunity
    • The adaptive immune system
      • Immunological specificity & memory
      • B cells & humoral immune response
      • T cells & cell-mediated immune response
    • The concepts of ‘self/non-self’ & ‘self-tolerance’
    The immune system – an overview
  • 4. Basic concepts in Immunology
    • Organisms and microorganisms
      • Bacteria, viruses, fungi & parasites
    • Infections and diseases
    • Infection == disease
    • Mechanisms of defense
    • The immune system
      • Cells & soluble factors
    • Immunity and Immunology
  • 5. ‘ Immunity’
    • Original meaning:
      • “ exemption from taxes”
    • Other extended meaning:
      • “ diplomatic immunity”
    • In the context of Immunology:
      • collective mechanisms against diseases
  • 6. Edward Jenner (1749-1823) & The Discovery of Vaccination (1796) “ Vaccinia (cowpox)” & “ human smallpox”
  • 7. Eradication of smallpox (1979, WHO)
  • 8. Vaccination
    • A process of induction of immunity to a pathogen by
    • deliberate injection of a weaken, modified or related form of
    • the pathogen which is no longer pathogenic.
  • 9. Other historic events & important findings:
    • L. Pasteur (1880s)
      • Vaccines against cholera, and rabies
    • R. Kock (late 19 th century)
      • Infections caused by microorganisms
    • P. Ehrlich et al. (1890s)
      • Serum factors transfer of immunity
    • Behring & Kitasato (1890s)
      • Antibodies in serum bound to pathogens
    • Porter & Edelman (1960s)
      • Antibody structure
    • J. Gowans (1960s)
      • Immunological importance of lymphocytes
  • 10.  
  • 11. Size of the immune system?
  • 12. Dendritic cell (sentinel)
  • 13.  
  • 14. Lymph Node
  • 15.  
  • 16. The bursa of Fabricius in birds
  • 17. Cells, tissues and organs of the immune system
    • Immune cells are bone marrow-derived, & distributed through out the body
    • Primary lymphoid organs:
      • Thymus: T cell maturation
      • Bone marrow (bursa of Fabricius in birds): B cell maturation
    • Secondary lymphoid organs:
      • Lymph nodes
      • Spleen
      • Mucosal lymphoid tissues (lung, gut)
  • 18. Questions:
    • How may vaccines protect us from infections?
    • What may actually occur in our immune system following a vaccination?
  • 19. Types of immunity
    • Innate (natural) immunity
      • Phagocytes etc.
      • Early, rapid responses, but limited & ‘non-specifc’
    • Adaptive (acquired) immunity
      • Lymphocytes (B & T cells)
      • Take time but powerful - ‘ specificity + memory ’
  • 20. Measles attacks & immunological memory
  • 21. “ Memory” in adaptive immunity
    • 1 st infection  memory  2 nd infection
    • slow response fast response
    • pathogen proliferate pathogen killed
    • disease no disease
    • symptoms no symptom
  • 22. Memory & specificity – key features of the adaptive immunity
  • 23.  
  • 24. Immunological memory & vaccination
    • Natural infections:
    • 1 st infection  memory  2 nd infection
    • slow response fast response
    • pathogens multiply pathogens disposed
    • Symptoms/disease no disease
    • Vaccination  memory  nature infections
    • no disease fast response
      • pathogens disposed
      • no disease
  • 25. Vaccination protects us from infection by inducing the adaptive immune response, but bypassing the need for a primary infection
  • 26. Theoretical basis for immunological specificity and memory
    • Theory of Clonal Selection
    • Establishment of lymphocyte memory pool
  • 27. 1 2 4 3 Ehrlich’s “Side-chain Hypothesis” (1900)
  • 28. Burnet’s “Clonal Selection” Theory Each lymphocyte produces one type of Ag receptors only, antigen selects and stimulates cells carrying receptors specific for the antigen 1 n 2 2 2 2 2 2 2
  • 29. s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s
  • 30. Immunological memory
    • The ability of the immune system to respond more rapidly and effectively to specific pathogens that have been encountered previously.
    • Reflection of the pre-existence of a clonally expanded population (pool) of antigen specific lymphocytes.
  • 31.
    • Humoral immune responses
      • B cells and antibodies
    • Cell mediated immune responses
      • Cytotoxic T cell (Tc)
      • Helper T cells (T H )
    The adaptive immune mechanisms
  • 32.
    • The Immune Recognition Molecules of the Adaptive Immune System
    • Immunoglobulin (Ig)
      • B Cell Receptor (BCR)
      • Antibody (Ab)
    • T Cell Receptor (TCR)
    • Major Histocompatibility Complex (MHC)
  • 33.                                 B Cells work chiefly by secreting soluble substances known as antibodies (Ab)
  • 34. Ab basic structure domains
  • 35. Ab V and C regions
  • 36.
    • Neutralization: e.g. toxins, viruses
    • Opsonization: bind pathogens for recognition by other immune cells (e.g. phagocytes)
    Antibody functions
  • 37.  
  • 38.  
  • 39. Tc Target Tc
  • 40.  
  • 41. T H cells play a central role in the immune system
  • 42. CD4 + T cells in HIV infection
  • 43. Immunological tolerance
    • A state of unresponsiveness to a particular Ag - Ag specific
      • to Ags derived from body’s own tissues/cells - self tolerance
      • to pathogen-derived/foreign Ags
  • 44. The concepts of immunological ‘ self ’ & ‘ non-self ’
    • Immune system does not attack self tissues or cells under normal condition, but how?
      • Central tolerance – “thymic education”
      • Peripheral tolerance – failed-safe mechanisms
  • 45.
    • Early in life (foetal stage)
    • T cells are important, which develop in the thymus
    • TCR specificities: randomly generated  many auto-reactive
    • T cells recognize self components (Ag) in the thymus  removed
    • Non-self reactive cells  selected, matured & exported
    Central tolerance – “ thymic education”
  • 46.
    • Post-thymic “continuing education”
      • not all self Ags present in the thymus
      • some auto-reactive cells can escape
    • Mechanisms:
      • Deletion
      • Inactivation (anergy)
      • Suppression
    Peripheral tolerance
  • 47. Does the immune system mount responses simply to anything that is “non-self”? A question for thoughts:
  • 48.
    • Immunity:
    • Innate (natural)
    • Adaptive (acquired)
    • Humoral (B cells, Abs)
    • Cellular (T, NK, MQ)
    • The adaptive immunity:
    • Key features: specificity & memory
    • Types: humoral & cell-mediated responses
    • Key players: T & B lymphocytes
    • T H cells play a central role in the induction & maintenance of immune responses
    • Principle of vaccination:
    • Vaccination protects us from infection by inducing protective immunity, through establishment of specific immunological memory but bypassing the need for primary infection
    • Immunological tolerance:
    • Tolerance induction is Ag specific
    • Central & peripheral mechanisms
    Summary