Defense Against Infection Disease

1. Defense Against Infection Disease

2. Skin and mucous membranes • Both prevent pathogens from entering the body by creating a barrier • Skin (when unbroken)-almost all microorganisms are unable to penatrate it • Weak points are found in areas not covered by skin (these areas have other defenses) • Mucous traps microorganisms

3. E. Example: Lungs -When you are sick the mucous membrane and cilia transport mucous from the lungs to the throat -This is the mucous you cough up F. Example: Stomach -has a very acidic environment that traps and kills foreign pathogens G. Example: Eyes -tears contain lysozymes that destroy bacterial cell walls H. Example: Vagina -has mucous and an acidic environment to fight off pathogens

4. Blood Clotting (the process) • Injury to the body (a cut or scrape) • Clotting factors are produced from plasma, damaged cells and platelets • Plasma releases Ca++ and vitamin K • Damaged cells release thrombokinase • Thrombokinase and calcium produce thrombin

5. Blood Clotting (the process) F. Active thrombin will hydrolyse soluble fibrinogen G. Soluble fibrinogen becomes insoluble fibrin H. Fibrin traps erythrocytes and forms a blood clot over the wound I. See p. 825 (red book)

6. Phagocytic Leucocytes • Leucoctyes-white blood cells -the body’s defense against pathogens -found in blood and body’s tissues B. Phagocyte-a type of white blood cell that ingests foreign substances C. Phagocytosis-ingestion of invading organisms by phagocytes (cell eating) -through endocytosis

7. Antigens and antibodies A. Antigen-molecule recognized as foreign by the immune system -they stimulate the production of antibodies -often found on the surface of pathogens B. Pathogens-microscopic organisms that cause sickness C. Antibodies-globular proteins that recognize antigens (immunoglobulins)

8. Antibody Production A. Macrophages ingest antigens by endocytosis -macrophages-cells that move through tissue fibers, engulfing dead cells and microbes B. Macrophages attach antigens to MHC proteins and move them to the outside of the cell via exocytosis -MHC proteins-Major histocompatibility complex -MHC proteins are membrane bound proteins found on macrophages C. The antigens are displayed by the MHC proteins outside of the cell

9. Antibody Production D. The macrophage is an antigen presenting cell (APC) Macrophage Antigen MHC protein

10. Antibody Production E. Helper T-cells have receptors that bind to antigens presented by the APCs F. CD4 is a cell surface protein of the helper T cell that helps the interaction of the macrophage CD4 Macrophage and MHC Helper T-cell (TH)

11. Antibody Production G. Once the T cell recognizes the antigen and binds to the macrophage, the macrophage sends a signal to the T cell H. The signal causes the T-cell to change from inactive to active • The signal causes the secretion of interleukin-1, a cytokine, by the macrophage -cytokines are signaling molecules J. The activated T cell then interacts with a B cell that has receptors for the same antigen

12. #5. Antibody Production K. Activated T cells send a signal to the B cell to activate them L. Once B cells are activated they begin to proliferate to produce clones of plasma cells and memory cells B cell Activated helper T-cell

13. #5. Antibody Production M. Plasma cells are activated B-cells without antigen receptors -their primary function is to secrete antibodies via exocytosis -these cells are found in large numbers and are short lived N. B-cells also produce memory cells -these cells are long lived and have specific antigen receptors -if the same antigen appears again they respond faster, stronger and for a more prolonged time

14. #6. B-cell and T-cells • B-cells-produced in bone marrow -several types 1. plasma b-cells 2. memory b-cells B. T-cells-produced in bone marrow and move to the thymus where they mature -several types 1. T-helper cells-help B-cell w/antibody production 2. Cytotoxic T-cells-directly kill pathogens

15. Location of thymus Primary function: • Process and manufacture cells for immune system (t-cells)

16. Macrophage and helper t-cell ANIMATION-McGRAW-HILL

17. Cytotoxic T-cells • Kill pathogens and viruses that have invaded cells • Can also kill cancerous cells • Cells that have been infected have remnants of the pathogen on their exterior and display specific proteins on their surfaces

18. Cytotoxic T-cells D. When a virus invades an organism, it invades their cells E. T-helper cells cannot recognize the pathogen to activate the B-cells for antibody production F. Instead the cell displays a different marker protein G. They cytotoxic t-cells then destroy the entire cell H. Miscellaneous animations

19. Cytotoxic T-cells and cancer A. Cytotoxic t-cells can be separated from a person’s blood and cultured in a lab B. The cells can be given to cancer patients to destroy tumor cells

20. Types of Defense • Active Immunity-caused by antibodies produced by the body’s own immune system (after the invasion of pathogens) -You have active immunity after recovering from an infectious disease -Takes time to develop -Example: If you get the chicken pox, you are unlikely to get it again because you body has already produced antibodies to destroy the foreign pathogen

21. People with chicken pox

22. #9. Types of Defense B. Passive immunity-gaining of antibodies from another organism in which active immunity has been established -Lasts only as long as the other organisms antibodies are present -Example: When a woman is pregnant she will pass some of her antibodies to the child through the placenta -Also when a woman breastfeeds she will pass some antibodies through breast milk

23. #9. Types of Defense C. Natural immunity-immunity gained through an infection D. Artificial immunity-immunity gained through vaccination

24. #9. Types of Defense E. Natural active immunity -gain immunity by producing own antibodies after an infection F. Artificial active immunity -gain immunity through vaccination G. Natural passive immunity -gain immunity through placenta or colostrum H. Artificial passive immunity -obtain antibody from another organism

25. #9. Types of Defense H. Artificial passive immunity -Example: If a person has survived malaria, they have antibodies -If another person contracts malaria and has not produced antibodies, they may be able to take antibodies from another person’s blood

26. #9. Types of Defense H. Artificial passive immunity -Example: If a person is bitten by a rabid animal, they can be injected with antibodies from a person who has already been vaccinated -This type of immunity combined with active immunity may save a person’s life -Injected antibodies fight off the virus until the person’s immune system can catch up

27. Review • State the difference between an antigen and an antibody. [1] • Explain how the skin and mucous membranes prevent entry of pathogens into the body. [3] • Explain why antibiotics are used to treat bacterial but not viral diseases. [2] • Define the terms active, passive, natural and artificial immunity. [4] • Explain antibody production. [5] • State one example of an infectious disease caused by a member of each of the following groups: virus, bacteria, fungus and protozoa. [4]

28. #10. Vaccination (Immunization) • Made of inactivated bacterial toxins, killed microbes and viable but weakened microbes • They can no longer cause disease but their antigens are still present • Work by stimulating an immune response and creating memory B cells • The secondary response (if a person becomes infected for real) will be much quicker for a person that has been vaccinated

29. #11. Benefits and Dangers of Vaccination • Benefits -eradication of diseases (Example: smallpox) -reduce human suffering -reduce monetary spending on treatments -prevent death by disease -prevent long term disabilities Smallpox lesions on skin of trunk. Picture taken in Bangladesh, 1973. Public Health Images Library (PHIL) ID # 284. Source: CDC/James Hicks

30. #11. Benefits and Dangers of Vaccination B. Dangers -increases in vaccination may reduce the ability of the immune system to fight off new infections -immunity developed after vaccination may not be as effective as ones own active immunity -vaccination of children could make them more susceptible as adults -possible side effects (Example: The MMR vaccination may increase autism.)

31. #11. Benefits and Dangers of Vaccination B. Dangers (continued) -people infected with live vaccines may pass pathogens in feces or blood -people may unknowingly not respond to the vaccination and could put themselves in harms way -pathogens may mutate and require new vaccines (Example: the flu)

32. Classwork • Get your book (black and red). • Go to p. 856 • Read ‘Methods: Monoclonal Antibody Technology’ • Explain the process of monoclonal antibody production

33. #12. Monoclonal antibodies A. Monoclonal antibodies = antibodies that are secreted from B cell clones that are specific for one antigen only

34. #13. Monoclonal antibody production • Inject a mammal with an antigen -Ex: Inject a mouse with human red blood cells (Type A) B. The mammals plasma cells will produce antibodies against the antigen -Ex: The mouse’s plasma cells will produce antibodies against Type A human blood

35. #13. Monoclonal antibody production C. Extract the plasma cells from the mammal D. Fuse the plasma cells with B-cell tumor cells -Tumor cells must be used because the continuously divide. E. Hybridoma cells are formed -Hybridoma cells are made in the lab by fusing normal cells with cancer cells, in order to combine the features of each -Example: Cancer cells multiply rapidly and the plasma cells dictate which antibody is produced

36. #13. Monoclonal antibody production F. The cells will grow in culture and continue to produce the same antibodies Ex: The mouse’s normal plasma cells are fused with human B cell tumor cells. The plasma cells will continue to replicate with the cancer B cells to produce antibodies to fight off the Type A human blood

38. Some animations 1. Antibody production 2. Cytotoxic t-cells 3. Monoclonal antibody production

39. #14. Human use of hybridoma cells • Blood typing • Add human blood to the antibodies from the mouse that was injected with human Type A blood • If the blood clots (a reaction to the antibodies) you will know that the blood was also Type A • This works because the mouse’s B cells recognized human Type A blood as a pathogen, causing it to produce antibodies against it • When you mix the mouse’s antibodies with human type a blood it will clot

40. #14. Human use of hybridoma cells B. Pregnancy testing 1. Pregnancy tests are made with monoclonal antibodies against hCG 2. hCG= human chorianic gonadotropin -a hormone produced during pregnancy -is manufactured by cells from the placenta -hCG can be detected in the urine 12- 14 days after conception

41. #14. Human use of hybridoma cells B. Pregnancy testing 3. hCG antibodies are placed on a testing strip or stick 4. Urine is added to the testing strip 5. If hCG is present in the urine it will attach to the hCG antibodies and cause a reaction 6. The reaction in pregnancy tests are normally designed to change color to show a positive test

42. #14. Human use of hybridoma cells B. Pregancy testing 7. False-negative results can occur if the hCG antibody test is given too early (hCG levels are not high enough) or the urine is too dilute C. Link 1 D. Link 2

43. #15. Five Classes of Antibodies (Immunoglobulins) • IgA -function: prevent virus and bacteria attachment to epithelial surfaces -found in: body secretions (saliva, perspiration, breast milk and tears) -in breast milk it can help protect infants from gastrointestinal infections -common antibody -shaped in the form of two Y shaped monomers and is called a dimer -has 4 antigen binding sites

44. #15. Five Classes of Antibodies (Immunoglobulins) B. IgD -function: antigen receptors on B-cells -initiate differentiation of B-cells into plasma cells and memory cells -found on B-cell surface -rare in abundance -monomers -2 antigen binding sites

45. #15. Five Classes of Antibodies (Immunoglobulins) C. IgE -function: cause cells to release histamines (chemicals released by cells as part of an allergic reaction) -allergic reaction: when the body’s immune system is hyperactive and over-reacts to foreign ‘things’ -symptoms: stuffy nose, watery eyes, rosy cheeks, airway constriction -treatment: take an anti-histamine

46. #15. Five Classes of Antibodies (Immunoglobulins) C. IgE (cont.) -very rare antibody -monomers -two antigen binding sites

47. #15. Five Classes of Antibodies (Immunoglobulins) D. IgG -functions: protect against bacteria, viruses and other toxins moving through the blood and lymph -antitoxins-antibodies that neutralize toxins -agglutinates- antibodies that clump together bacteria and other foreign substances

48. #15. Five Classes of Antibodies (Immunoglobulins) D. IgG -found in: blood and other tissue (can cross the placenta) -very common antibody -monomer -two antigen binding sites

49. #15. Five Classes of Antibodies (Immunoglobulins) E. IgM -functions: agglutination (very efficient at this because it has 10 antigen binding sites) -found in: blood (too large to cross placenta) -first antibodies to appear and their concentration declines quickly -good diagnostic indicator: indicates a current infection, because pathogen presence cause their formation -a pentamer -has 10 antigen binding sites