Innate Immunity - ‫بسم اللة الرحمن‬...

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Unformatted text preview: ‫بسم اللة الرحمن‬ ‫الرحيم‬ Innate Immunity Innate Immunity Innate Immunity Innate Defensive mechanisms include : 1) Innate immunity (Natural or Non specific) 2) Acquired immunity (Adaptive or Specific) Cell­mediated immunity Humoral immunity Component of Innate Immunity Component Innate Immune system First line Second line 1) Mechanical barriers A­ cells 2) Chemical & biochemical inhibitors 1­ Natural killer 3) Normal flora 2­ Phagocytes B­ Soluble factors C­ Inflammatory barriers First line First 1) Mechanical barriers ­ Intact skin ­ Mucous coat ­ Mucous secretion ­ Blinking reflex and tears ­ The hair at the nares ­ Coughing and sneezing reflex First line First 2) Chemical & biochemical inhibitors ­ Sweet and sebaceous secretion ­ Hydrolytic enzymes in saliva ­ HCl of the stomach ­ Proteolytic enzyme in small intestine ­ Lysozyme in tears ­ Acidic pH in the adult vagina First line First 3) Normal bacterial flora ­ Competition for essential nutrients ­ Production of inhibitory substances Second line Second A) cells 1­ Natural killer (NK) Definition: Large granular lymphocytes Innate cytotoxic lymphocytes Source : Bon marrow precursors Location : 10% or 15% of lymphocytes in peripheral blood 1% or 2% of lymphocytes in spleen Tumor cells Function : Cytotoxic for Viral infected cells Bacterial, fungal, parasitic infection Responsible for antibody–dependent cell mediated cytotoxicity (ADCC) Second line Second 2­ Phagocytes Specialized cells for capture, Ingestion and destruction of invading microorganisms * Polymorphoniclear leucocytes, mainly neutrophils: granulocytes circulate in blood * Mononuclear cells (macrophages) ­ Monocytes in blood ­ Histocytes in connective tissues Fixed reticuloendothelial cells ­ in liver spleen, lymph nods, bon marrow Second line Second B­ Soluble factors 1­ Acute phase protein (Plasma protein, CRP=C reactive protein, Fibrin.) 2­ Complement (proteins in serum, body fluids) 2­ Interferons (Proteins against viral infections) 3­ Properdin (Complement activation) 4­ Beta lysine (Antibacterial protein from Platelets) 5­ Lactoferrrin,Transferrin (Iron binding protein) 6­ Lactoperoxidase (Saliva & Milk) 7­ Lysozyme (Hydrolyze cell wall) Interferons Interferons Proteins usually produced by virally infected cells * Types of interferons: 1­ Alpha interferon Secreted by Macrophages Induced by Viruses or Polynucleotide 2­ Beta interferon Secreted by Fibroblasts, Viruses 3­ Gamma interferon T­ lymphocytes, Specific antigens Interferons Interferons Protective action of interferons: 1) Activate T­cells 2) Activate macrophages 3) Activate NK Phagocytosis Phagocytosis The engulfment, digestion, and subsequent processing of microorganisms by macrophages and neutrophils 1) Chemotaxis & attachment: a­ Attraction by chemotactic substances (microbes, damaged tissues) b­ Attachment by receptors on surfaces Phagocytosis Phagocytosis 2) Ingestion: * Phagocyte pseudopodia surround organism forming phagosom * Opsinins and co­factors enhance phagocytosis * Fusion with phagocyte granules and release digestive, toxic contents Phagocytosis Phagocytosis 3­ Killing (two microbicidal routes) a­ Oxygen depended system (powerful microbicidal agents) Oxygen converted to superoxide, anion, hydrogen peroxide, activated oxygen and hydroxyl radicals. b­ Oxygen­independent system (anaerobic conditions) Digestion and killing by lysozyme. Lactoferrin, low pH, cationic proteins and hydrolytic and proteolytic enzymes C) Inflammatory Barriers C) * Tissue damage by a wound or by invading pathogen * Inflammatory response: Tissue damage Release of chemical mediators from Leukocytes (Histamine, fibrin, kinins, cytokines) Invading microbe Redness of tissue Tissue temperature Vasodilatation of capillaries Capillary permeability Influx of fluids Influx of phagocytes into tissues Thanks Thanks ...
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This note was uploaded on 12/21/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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