1 / 13

Protective Immunity To Microorganisms

Protective Immunity To Microorganisms. Defense against microbes is mediated by: Innate immunity and acquired immunity Humoral immunity (antibodies)Through both Cell mediated immunity

justise
Download Presentation

Protective Immunity To Microorganisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


    2. Protective Immunity To Microorganisms

    3. Protective Immunity To Microorganisms Defense against microbes is mediated by: Innate immunity and acquired immunity Humoral immunity (antibodies) Through both Cell mediated immunity (CMI)

    4. Antibacterial Immunity I) Immunity to extracellular bacteria: 1- The innate immunity: a- Complement activation b- Phagocytosis c- The inflammatory response

    5. I) Immunity To Extracellular Bacteria 2- The acquired immune responses: i-The humoral mechanisms (antibodies) “main role” ii- Cell mediated immune response “less role” i- Antibodies induce immunity through: a- Neutralization of bacterial toxins b- Antibodies attach to the surface of bacteria and; - Act as opsonins, enhance phagocytosis (Opsonization) - Prevent adherence of bacteria to their target cells e.g. IgA on mucosal surfaces - Activation the complement leading to bacterial lysis - Agglutinate bacteria, preventing their spread and facilitating phagocytosis

    6. I) Immunity To Extracellular Bacteria ii- Cell mediated immune mechanisms: * Microbes are internalized by APCs and presented to TH * TH cells are activated and release cytokines which; - activate phagocytosis their microbicidal functions - Stimulate antibody production - Induce local inflammation

    7. Immunity To Intracellular Bacteria 1) Innate immunity It is mainly by natural killer (NK) cells - They kill infected cells and secrete IFN-? - IFN-? activate phagocytosis to kill intracellular microbe E.g. tuberculosis, leprosy, listeriosos 2) Acquired immunity is manly by CMI - Activation of macrophages to kill intracellular microbes - Lysis of infected cells by cytotoxic cells (CTLs) - Most of these organisms are resistant to phagocytosis, cause chronic infection and granuloma formation

    8. Anti-Viral Immunity 1) Humoral immunity: a- Virus neutralization * In viraemic infections, Antibodies neutralize virus, preventing its attachment to receptor sites on susceptible cells e.g. Poliovirus, mumps, measles, rubella * In superficial non-viraemic infections (infleunza) Secretory IgA neutralizes virus infectivity at the mucous surfaces

    9. Anti-Viral Immunity 1) Humoral immunity: b- Antibodies destroy free virus particles directly by: i- Aggregation of virus and opsonization ii- Complement mediated lysis * Both mechanisms also act on virus infected cells

    10. Anti-Viral Immunity 2) Cell mediated immunity: Cell mediated cytotoxicity, mediated by : - Cytotoxic T-cells (CTLs) - NK cells - Activated macrophages

    11. Anti-Viral Immunity CMI acts on virus infected cells through: - CTLs kill virus infected cells directly after recognition of viral antigens on cell surface in association with MHC I - TH-cells stimulated by viral antigens release cytokines Cytokines attract and activate macrophages to kill virus infected cells - Nk-cells destroy virus infected cells early in infection before appearance of antibodies - Antibody-dependent cell mediated cytotoxicity (ADCC): Antibody binds to virus infected cells such cells are lysed by NK cells, macrophages and polymorphs

    12. Anti-Viral Immunity 3) Anti-viral activity of interferons (IFNs) 1- Virus infected cells produce INF-a; - INF-a inhibit intracellular replication of viruses - IFN-a activate NK-cells to kill virus infected cells - IFNs have no direct effect on extracellular virus - IFNs act early in viral diseases before antibody - INFs activity is not specific

    13. Anti-Fungal Immunity Immune response to fungi consist mainly of : 1) Innate immunity is mediated by: - Neutrophils and macrophages - Fungi are readily eliminated by phagocytes 2) Acquired immunity (cell mediated immunity) - CMI acts in a manner similar to its action against intracellular bacteria * Disseminated fungal infection are seen in: immunodifcient persons

    14. Thanks

More Related