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Acquired immunity

Acquired immunity






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  • We will focus on adaptive responses. All these feature of an adaptive response require very specific interactions of molecules. Will describe B and T cells and their roles. Immunological memory - vaccination
  • The important difference between B and T cells is how they can recognize antigens.
  • • Antibody producing, have membrane bound antibodies, proliferation......., memory – plasma, point out the molecular interactions.
  • • Has a T-cell receptor – only recognition of antigens together with MHC molecules. Explain how this work and the difference between class I and class II molecules. Point out the importance of molecular interaction. Explain how Th cells can help B cells - drawing
  • Draw the pictures!!!!

Acquired immunity Acquired immunity Presentation Transcript

  • Acquired Immunity
  • The immune system Immune system
    • Anatomic barriers (Skin, mucous membranes)
    • Physological barriers (temperature, pH)
    • Phagocytic Barriers (cells that eat invaders)
    • Inflammatory barriers (redness, swelling, heat and pain)
    • Antigen specificity
    • Diversity
    • Immunological memory
    • Self/nonself recognition
    Innate (non-specific) immunity Adaptive (specific) immunity
  • Humoral and cellular immunity (antibody mediated or cellular)
  • B cells B-cell Surface bound antibody Antigen Antibody secreting B cell Soluble antibodies, circculate in the body
  • Plasma cell Virus killed B-cell
  • T cells
    • Two types:
      • Helper T cells (Th): activates other cells
      • Cytotoxic T cells (Tc): can kill other cells
    • T cells can only recognize antigens associated with certain molecules (MHC)
  • Presentation of antigens to T cells
    • Proteins (peptides) from inside the cell are presented by MHC I molecules to Tc cells.
    • Proteins (peptides) from the outside of cells are presented by MHC II molecules to Th cells.
    • MHC I on almost all cells
    • MHC II on specialized antigen-presenting cells
    • The resistance that an individual acquires during life
    • Two types :
    • 1. Active Immunity
    • 2. Passive Immunity
    • Active Immunity : Resistance developed as a result of antigenic stimulus
    • Passive Immunity : Resistance transmitted passively in ready made form
    • Active Immunity
    • - Adaptive immunity : Adaptive response of host to specific pathogen or antigen
    • - Active functioning of the host’s immune apparatus, synthesis antibodies and immunologically active cells
    • - Latent period
    • - Negative phase
    • - Long lasting
    • - Secondary response is faster
    • - Immunological memory
    • - More effective and gives better protection
    • Passive Immunity
    • Ready made form of immunity
    • Recipients immune system plays no active role
    • No antigenic stimulus
    • No latent period, protection effective immediately
    • No negative phase
    • Transient , lasting for few weeks to days
    • No secondary response, diminishes with repetition
    • Less effective and Inferior o active immunity
    • Acts immediately and ‘Instant form of Immunity’
    • Active Immunity
    • Natural Active Immunity :
    • - Results from a clinical or inapparent infection by microbe
    • - Measles and Poliomyelitis
    • - Life long following many viral infection
    • - Immunity following bacterial infection is less permanent than viral infections
    • - Premunition : Immunity to re infection lasts till the original infection remain active. Eg: Syphilis
    • - In Chancroid : no effective immunity against re infection even during active infection
    Natural Active Immunity Artificial Active immunity
    • Artificial Active Immunity
    • - Resistance induced by Vaccines – live or killed microorganisms or their products
    • - Live vaccines : Parallels natural infection
    • - Gives protection for a long period
    • - requires booster doses
    • - Killed vaccines : Less immunogenic
    • - Protection lasts for a short period
    • - Repeated doses required
    • - Parenteral administration required to initiate humoral antibody response
    • Passive Immunity
    • Natural passive immunity :
    • - Mother to baby : Maternal antibodies, Colostrum
    • - Immunological independence at 3-6 months
    • - Active immunization of mothers during pregnancy improves the passive immunity in infants
    • - Tetanus toxoid in tetanus prone communities
    Natural Passive Immunity Artificial Passive Immunity
    • Artificial Passive Immunity :
    • Administration of antibodies
    • - Hyper immune sera
    • - Hyper immune globulin
    • - Convalescent sera
    • - Pooled Human gamma globulin
    • Treatment of infections in non immune persons
    • Confers immediate and Temporary protection
    • Suppression of active immunity in Erythroblastosis fetalis
  • Passive Immunity
    • Antibodies are obtained from someone else
      • Conferred naturally from a mother to her foetus
      • Conferred artificially from immune serum or gamma globulin
    • Immunological memory does not occur
    • Protection provided by “borrowed antibodies” is temporary.
  • Active and Passive Immunity/Vaccines Slide 12.34
    • B cells encounter antigens and produce antibodies
    • Active immunity can be naturally or artificially acquired
    • Combined Immunization :
    • Active & Passive
    • Adoptive immunity : Injection of immunologically competent lymphocytes (Transfer factor)
    • Measurement of immunity
    • - Antibody titers by
    • - Agglutination & Precipitation
    • - CFT, HI
    • - NT & ELISA
    • Local Immunity
    • Herd Immunity