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بسم اللة الرحمن الرحيم
<ul><li>Protective Immunity </li></ul><ul><li>To  </li></ul><ul><li>Microorganisms </li></ul>
Protective Immunity To Microorganisms <ul><li>Defense against microbes is mediated by: </li></ul><ul><li>Innate immunity  ...
Antibacterial Immunity <ul><li>I) Immunity to extracellular bacteria: </li></ul><ul><li>1- The innate immunity: </li></ul>...
I) Immunity To Extracellular Bacteria <ul><li>2- The acquired immune responses: </li></ul><ul><li>i-The humoral mechanisms...
I) Immunity To Extracellular Bacteria <ul><li>ii- Cell mediated immune mechanisms: </li></ul><ul><li>*  Microbes  are  int...
Immunity To Intracellular Bacteria <ul><li>1) Innate immunity </li></ul><ul><li>It is mainly by natural killer (NK) cells ...
Anti-Viral Immunity <ul><li>1) Humoral immunity: </li></ul><ul><li>a- Virus neutralization </li></ul><ul><li>*  In viraemi...
Anti-Viral Immunity <ul><li>1) Humoral immunity:   </li></ul><ul><li>b-  Antibodies  destroy free virus particles directly...
Anti-Viral Immunity <ul><li>2) Cell mediated immunity: </li></ul><ul><li>Cell mediated cytotoxicity , mediated by : </li><...
Anti-Viral Immunity <ul><li>CMI acts on virus infected cells through: </li></ul><ul><li>-  CTLs kill  virus  infected cell...
Anti-Viral Immunity <ul><li>3) Anti-viral activity of interferons (IFNs) </li></ul><ul><li>1- Virus infected cells produce...
Anti-Fungal Immunity <ul><li>Immune response to fungi consist mainly of : </li></ul><ul><li>1) Innate immunity is mediated...
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Protective immunity to microbes.ppt

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Protective immunity to microbes.ppt

  1. 1. بسم اللة الرحمن الرحيم
  2. 2. <ul><li>Protective Immunity </li></ul><ul><li>To </li></ul><ul><li>Microorganisms </li></ul>
  3. 3. Protective Immunity To Microorganisms <ul><li>Defense against microbes is mediated by: </li></ul><ul><li>Innate immunity and acquired immunity </li></ul><ul><li>Humoral immunity (antibodies) </li></ul><ul><li>Through both </li></ul><ul><li>Cell mediated immunity (CMI) </li></ul>
  4. 4. Antibacterial Immunity <ul><li>I) Immunity to extracellular bacteria: </li></ul><ul><li>1- The innate immunity: </li></ul><ul><li>a- Complement activation </li></ul><ul><li>b- Phagocytosis </li></ul><ul><li>c- The inflammatory response </li></ul>
  5. 5. I) Immunity To Extracellular Bacteria <ul><li>2- The acquired immune responses: </li></ul><ul><li>i-The humoral mechanisms ( antibodies ) “main role” </li></ul><ul><li>ii- Cell mediated immune response “less role” </li></ul><ul><li>i- Antibodies induce immunity through: </li></ul><ul><li>a- Neutralization of bacterial toxins </li></ul><ul><li>b- Antibodies attach to the surface of bacteria and; </li></ul><ul><li>- Act as opsonins , enhance phagocytosis (Opsonization) </li></ul><ul><li>- Prevent adherence of bacteria to their target cells </li></ul><ul><li>e.g. IgA on mucosal surfaces </li></ul><ul><li>- Activation the complement leading to bacterial lysis </li></ul><ul><li>- Agglutinate bacteria , preventing their spread and </li></ul><ul><li>facilitating phagocytosis </li></ul>
  6. 6. I) Immunity To Extracellular Bacteria <ul><li>ii- Cell mediated immune mechanisms: </li></ul><ul><li>* Microbes are internalized by APCs and presented to TH </li></ul><ul><li>* TH cells are activated and release cytokines which; </li></ul><ul><li>- activate phagocytosis their microbicidal functions </li></ul><ul><li>- Stimulate antibody production </li></ul><ul><li>- Induce local inflammation </li></ul>
  7. 7. Immunity To Intracellular Bacteria <ul><li>1) Innate immunity </li></ul><ul><li>It is mainly by natural killer (NK) cells </li></ul><ul><li>- They kill infected cells and secrete IFN- γ </li></ul><ul><li>- IFN- γ activate phagocytosis to kill intracellular microbe </li></ul><ul><li>E.g. tuberculosis, leprosy, listeriosos </li></ul><ul><li>2) Acquired immunity is manly by CMI </li></ul><ul><li>- Activation of macrophages to kill intracellular microbes </li></ul><ul><li>- Lysis of infected cells by cytotoxic cells (CTLs) </li></ul><ul><li>- Most of these organisms are resistant to phagocytosis, cause chronic infection and granuloma formation </li></ul>
  8. 8. Anti-Viral Immunity <ul><li>1) Humoral immunity: </li></ul><ul><li>a- Virus neutralization </li></ul><ul><li>* In viraemic infections, </li></ul><ul><li>Antibodies neutralize virus, preventing its attachment </li></ul><ul><li>to receptor sites on susceptible cells </li></ul><ul><li>e.g. Poliovirus, mumps, measles, rubella </li></ul><ul><li>* In superficial non-viraemic infections (infleunza) </li></ul><ul><li>Secretory IgA neutralizes virus infectivity at the mucous surfaces </li></ul>
  9. 9. Anti-Viral Immunity <ul><li>1) Humoral immunity: </li></ul><ul><li>b- Antibodies destroy free virus particles directly by: </li></ul><ul><li>i- Aggregation of virus and opsonization </li></ul><ul><li>ii- Complement mediated lysis </li></ul><ul><li>* Both mechanisms also act on virus infected cells </li></ul>
  10. 10. Anti-Viral Immunity <ul><li>2) Cell mediated immunity: </li></ul><ul><li>Cell mediated cytotoxicity , mediated by : </li></ul><ul><li>- Cytotoxic T-cells (CTLs) </li></ul><ul><li>- NK cells </li></ul><ul><li>- Activated macrophages </li></ul>
  11. 11. Anti-Viral Immunity <ul><li>CMI acts on virus infected cells through: </li></ul><ul><li>- CTLs kill virus infected cells directly after recognition of viral antigens on cell surface in association with MHC I </li></ul><ul><li>- TH-cells stimulated by viral antigens release cytokines Cytokines attract and activate macrophages to kill </li></ul><ul><li>virus infected cells </li></ul><ul><li>- Nk-cells destroy virus infected cells early in infection before appearance of antibodies </li></ul><ul><li>- Antibody-dependent cell mediated cytotoxicity (ADCC): </li></ul><ul><li>Antibody binds to virus infected cells such cells are lysed by NK cells, macrophages and polymorphs </li></ul>
  12. 12. Anti-Viral Immunity <ul><li>3) Anti-viral activity of interferons (IFNs) </li></ul><ul><li>1- Virus infected cells produce INF- α ; </li></ul><ul><li>- INF- α inhibit intracellular replication of viruses </li></ul><ul><li>- IFN- α activate NK-cells to kill virus infected cells </li></ul><ul><li>- IFNs have no direct effect on extracellular virus </li></ul><ul><li>- IFNs act early in viral diseases before antibody </li></ul><ul><li>- INFs activity is not specific </li></ul>
  13. 13. Anti-Fungal Immunity <ul><li>Immune response to fungi consist mainly of : </li></ul><ul><li>1) Innate immunity is mediated by: </li></ul><ul><li>- Neutrophils and macrophages </li></ul><ul><li>- Fungi are readily eliminated by phagocytes </li></ul><ul><li>2) Acquired immunity (cell mediated immunity) </li></ul><ul><li>- CMI acts in a manner similar to its action against </li></ul><ul><li>intracellular bacteria </li></ul><ul><li>* Disseminated fungal infection are seen in: immunodifcient persons </li></ul>
  14. 14. <ul><li>Thanks </li></ul>

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