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Immune 20132014 (1)
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- 2. The immune system • Whatis the main function of the immune system? • What is a pathogen?
- 3. The defense mechanisms • 1stline vs 2nd line vs 3rd line of defenses
- 4. Give the functionof these cells • Monocytes APC coelomocytes • Macrophages Basophil • Neutrophil Eosinophil • Mast cell NK cell • Cytokine cytotoxic T cell • effector cell helper T cell • memory cell suppressor T cell
- 5. The chemicals andothers • Perforin Chemokine • Interferon antibody • Antigen antigen receptor • Cd4 Cd8 • Histamine Interleukin • Lysozyme prostaglandins • Pyrogens Rh factor
- 6. The innate immunity • Whathappens to you if you caught a virus or an infection?
- 7. Inflammation and Sepsis • Releaseof histamines (pathogen/self cell) • Dilation and inc permeability of BV (prostaglandin) • Increased blood flow • Inflammation (redness and swelling)
- 8. Phagocytic cells • Neutrophils arefirst to arrive • Macrophages will also arrive
- 9. Chemokines • Messenger chemical • Attracts phagocyticcells • Activation of lysozyme action
- 10. Severe infection • Fever isan immune response to severe infection – Can be caused by the pathogens – May be due to pyrogens released by some leukocytes – Can facilitate phagocytosis Septic shock- high fever, hypotension
- 11. Antimicrobial proteins • Proteins thatattack microbes or stall reproduction of microbes • Lysozyme is an example • Also, presence of the complement system – Made up of 20 serum proteins – Action: lysis or attraction of phagocytic cells – Is also part of specific immune response
- 12. Interferons – Secreted by virus-infectedcells – Neighboring cells are stimulated to produce chemicals that can inhibit viral infection – Not virus-specific – A specific type of interferon activates phagocytes
- 13. Self vs Non-self • Haveyou asked yourselves the question who am I?
- 14. Self vs Non-self • Lymphocytesreact on special surface glycoproteins encoded by genes called Major Histocompatibilty Complex (MHC) • In Humans, Human Leukocyte Antigens (HLA) • Class I MHC- Almost all nucleated cells • Class II MHC- macrophages, B cells, activated T cells, cell in the interior of the thymus Varies from one person to another
- 15. Specific immunity: thethird line of defense • Lymphocytes- cells responsible for the specific immune response • There are two types: B cells and T cells (NK cells another type) • Antigen- molecules that elicit specific response from lymphocyte – E.g. Molecules from bacteria, fungi, virus, parasitic worms • Antigens activate B cell in producing antibodies
- 17. Recognition of antigensby B cells and T cells • Specificity is possible because of membrane- bound antigen receptor • B cell antigen receptor- transmembrane version of antibodies – Also called membrane antibodies • T cell antigen receptor- called T cell receptor – Structurally related to membrane antibodies – T cell receptor never released in secreted form
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- 19. Clonal selection • Antigen bindsto a specific antigen receptor (B cell) • B cell produces its clone • Some B cells become plasma cells (short-lived) that can secrete antibodies to the specific antigen – Plasma cells- also called effector cells • Some B cells become memory cells (long-lived) for re-exposure to the antigen
- 20. Immunological memory • Primary immuneresponse- selective proliferation and differentiation of lymphocytes upon first exposure – 10-17 days to develop maximum effector cells – Selected B cells and T cells produce their respective effector cells
- 21. Immunological memory • Secondary immuneresponse- re-exposure to the same antigen – response is faster, greater magnitude, more prolonged – Also, more antibodies are produced – Antibodies have greater affinity to the antigens – Secondary response is called immunological memory
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- 23. Lymphocyte development • All bloodcells develop from pluripotent cells • Lymphocytes also develop from pluripotent cells • T cells- mature in the thymus • B cells- mature in the bone marrow
- 24. Immune tolerance forself • Maturing lymphocytes’ antigen receptors are rendered non-functional • If antigen receptors cannot be switched off, lymphocytes undergo apoptosis
- 25. The other cells.... • CytotoxicT cells- kill cells through lysis • Helper T cells- bind to antigen cell and secretes cytokine • Antigen-presenting cells (APCs)- engulf bacteria (virus) and present fragment of these pathogens to other lymphocytes
- 26. Humoral response andcell-mediated response • Humoral immunity- involves B cell activation, production of antibodies in blood plasma and lymph called humor • Cell-mediated immunity- action of T cells
- 27. Overview of humoralresponse • Macrophage engulfs the pathogen • Class II MHC binds to fragment of pathogen • MHC-antigen complex is presented by the phagocytic cell • A helper T cell with specific receptor for the antigen makes contact with the macrophage and releases cytokines
- 28. Overview of humoralresponse • Activated T cell presents the antigen to a B cell • Cytokines activates the B cell • Activated B cells differentiate into plasma and memory cells • Plasma cells will produce the specific antibodies
- 29. Cell-mediated immune response • Occurswhen antigen displayed by APC activates Cytotoxic T cell • Cytotoxic cell can differentiate to Memory T cells or active cytotoxic T cells • Active against cancer cells and pathogens • Kills these cell through lysis
- 30. Antibodies • Do not destroyantigens directly • Rather, neutralizes it or present it as a target for opsonization, agglutination, precipitation, or complement fixation, neutralization
- 31. Antibodies • Opsonization- coating ofantigens by antibodies to facilitate phagocytos • Neutralization- binds to the antigen and inactivates it • Agglutination- clumping of bacteria or virus to effectively neutralize or opsonize it • Complement fixation or precipitation- immune adherence occurs – Microbes coated with antibodies and complement
- 32. The ABO bloodtype • A and B are the antigens • Type A has antigen A and antibody B • Type B has antigen B and antibody A • Type AB has both antigen but no antibody • Type O has no antigen but has both antibody IgM not IgG
- 33. Rh Factor IgG cancross the placenta ++ = + +- = + - - = -
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Editor's Notes
- #14 Self recognition is important in an immune response Presence of receptors/markers in pathogens that enter the body Very efficient, even undigested proteins are considered as antigens
- #18 Single lymphocyte has ~100,000 receptors for antigen Differentiation of unspecialized lymphocytes gives rise to diversity of the antibody or receptor Makes it possible to respond to different pathogens
- #21 Re-exposure- response is faster, greater magnitude and more prolonged