Introduction to Immunology

Introduction to Immunology

1. Cell of the Immune System

   • Leukocytes
     • Have nuclei and involved in phagocytosis, inflammation, adaptive immune response
   • Platelets
     • Do not have nuclei and involved in inflammation and blood clotting

2. Components of Immune System

   • Cardiovascular System
     • Include heart and blood vessels
   • Mononuclear Phagocyte System
     • Network of reticular fibres and Phagocytes
   • Lymphatic Syatem
     • Primary lymphoid organs are the production sites of immune cells and the maturation sites for immune cells in the absence of antigen
       • Exp- Bone marrow, thymus
     • Secondary lymphoid organs are the maturation sites for antigen-driven immune cells
       • Exp - adenoid, tonsils, lymph nodes, spleen, mucosa-associated lymphoid tissue (MALT)

3. Innate Immunity : First Line of Defence

   • Innate Immune Response - Non specific - Immune components are preformed - Response magnitude is similar during the first and subsequent encounters - No memory is stored
   • Involved external physical barriers

4. Innate Immunity : Second Line of Defence

   • Innate Immune Response - Non specific - Immune components are preformed - Response magnitude is similar during the first and subsequent encounters - No memory is stored
   • Internal physiological barriers and create hostile environment for the invaders
     • Antimicrobial proteins
       • The complement system
         • Classical, Lectin, Alternative
         • Work in cascade reactions to destroy phatogens
       • Interferons
         • Cytokines involved in immune regulation, particularly against viruses
       • Iron-binding proteins
         • Some bacteria employ siderophores, to "steal" iron from host proteins
       • Antimicrobial peptides
         • Short proteins, kill bacteria by inserting themselves into the membrane
         • Bacteriocins, Defensins, Magainins, Protegrins
     • Phagocytosis
       • They possess lysosome containing substances
         • Water, Lysozyme, Protease, Phosphatase, Nuclease, Lipase
     • Fever
       • Increased core temperature above 37'C and initiated by pyrogens
       • Reduced iron availability
         • Many pathogens requires iron and during fever, iron with holding occurs
       • Inhibition of microbial multiplication
         • Creating suboptimal temperature
       • Increase metabolic rate
         • Stimulate immune reations
     • Inflammation
       • Redness- from increased red blood circulation
       • Heat- given off by the increased blood flow
       • Pain- stimulation of nerve endings
       • Oedema- swelling caused by fluid escaping into the tisssues
       • Stage of inflamation
         • Vasodilation cause more blod delivered and redness and localized heat
         • Release of cytokines cause vasodilation and increase permeability of vessels
         • Certain cytokines also increase permeability of blood vessels

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