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

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