Immune system mic lec

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<ul><li> 1. IMMUNE SYSTEM MARLON M. MARAMION, MD, DPSP </li></ul> <p> 2. THE IMMUNE SYSTEM OBJECTIVES 1.Know the components of the immune system 2.Understand how each component functions in the elimination of microorganisms 3. IMMUNE SYSTEM PHYSIOLOGIC FUNCTION protect the body against infectious pathogens MECHANISM: INNATE IMMUNITY ADAPTIVE IMMUNITY 4. INNATE IMMUNITY Natural Immunity Defense mechanisms that are present even before infection and have evolved to specifically recognize microbes and protect multicellular organism against infection nonspecific FIRST LINE OF DEFENSE 5. Mechanisms of Innate Immunity PhysiologicBarriers at the Portal of EntrY - skin - mucous membranes Alternative Pathway of Complement Activation Phagocytosis Interferons Natural Killer (NK) Cells 6. SKIN acid pH and certain chemical substances (especially fatty acids) Lysozyme 7. MUCUS MEMBRANES Mucus &amp; cilia Secretions (saliva, tears) Lysozyme IgA antibody Phagocytes pH Normal flora 8. Reticuloendothelial System mononuclear phagocytic cells blood lymphoid tissues liver spleen bone marrow lungs and other tissues - FILTER BLOOD AND TISSUE 9. COMPLEMENT SYSTEM 10. COMPLEMENT SYSTEM OPSONIZATION MEMBRANE ATTACK COMPLEX FORMATION 11. PHAGOCYTOSIS polymorphonuclear leukocytes (granulocytes) phagocytic monocytes (macrophages) fixed macrophages of the reticuloendothelial system OPSONIZATION a. C3 component of the complement system b. Fc portion of antibody 12. NEUTROPHILS 60-70% of WBC 12-15 m Nucleus 2-5 lobes Lifespan 6-7 hrs Function- PHAGOCYTOSIS 13. NEUTROPHILS MICROBIAL KILLING 1. Non oxidative process - lytic enzymes - Lysozyme (destroys Peptidoglycan of bacterial cell wall) - Lactoferrin (binds iron) 2. Oxidative a. generation of H2O2- acted upon MPO + cofactors (halides) + acid = HOCl b. production of superoxide anion (O2 )- directly lethal for many microorganisms PUS 14. Monocytic (Mononuclear) Phagocytic System Principal cells Monocytes and Macrophages Monocytes circulate in the blood (1-3%) for a few days, then migrate in the tissues as macrophages 15. Macrophages Types Tissue and fixed macrophages Kupffer cells, histiocytes, splenic macrophage, alveolar macrophages, mesangial cells, microglial cells, osteoclasts Giant and epitheloid cells Granuloma formation 16. Macrophages Receptors Chemokines and cytokines Complement components Fc receptors Class I and II antigens for Ag presentation 17. Macrophages Activation By gamma interferon which are released by activated T helper 1 subset More efficient in intracellular killing activities 18. Macrophages Functions Phagocytosis Antigen processing Antigen presentation Secretory cells IL-1, IL-6, TNF-a 19. Phagocytosis 20. Phagocytosis Mechanisms Of Microbial Killing Oxygen-dependent reactions Myeloperoxidase-mediated MPO + H2O2 form aldehydes and hypochlorites which have powerful antimicrobial activity MPO-independent H2O2, superoxide anions, hydroxyl radicals and singlet O2 21. Phagocytosis Mechanism Of Microbial Killing Oxygen-independent reactions Intracellular accumulations of lactic acid Lysozymes Cationic proteins Lactoferrin and transferrin Ceruloplasmin LYTIC ENZYME 22. INTERFERONS Antiviral proteins Interferon (IFN- A) and interferon (IFN-B) &amp; interferon (IFN-G) produced by virally infected cells &amp; activated lymphocytes control viral replication by inhibiting protein synthesis &amp; viral multiplication. 23. Natural Killer Cells - 10-20% of the circulating lymphocytes - Larger than small lymphocytes - Abundant azurophilic granules RECEPTORS a. "activating receptor" - recognizes carbohydrate ligands b. "inhibitory receptor" - recognizes MHC class I molecules - Kill: Tumor cells Virally infected cells First line of defense 24. INNATE IMMUNE MECHANISM Phagocytosis Inflammation - IL-1 &amp; TNF release by macrophages - generation of prostaglandins - fever </p>