1. Defense against infectious disease SL/HL

2. Primary defense Skin – First line of defense against pathogens – Outer layer tough Protects against chemical & physical damage – Sebaceous glands Associated with hair follicles Secrete sebum – Maintains skin moisture and slightly lowers pH » Inhibits growth of bacteria

3. Primary defense Mucous membranes – Thinner, softer skin found in nasal passages, head of penis, vagina – Secrete mucous Sticky solution of glycoproteins Physical barrier Traps pathogens – Expelled by sneezing, swallowed, vaginal secretions – Antiseptic properties due to anti-bacterial enzyme lysozyme

4. Cut in blood vessel Blood escapes Body works to “seal” the cut Blood changes from liquid to semi-solid gel Describe the process of blood clotting

5. Blood clotting Clotting proteins prothrombin & fibrinogen PlateletsErythrocytes & Leucocytes

6. Video

7. Here’s how it works Damaged blood vessel Chemicals released Platelets adhere to damaged areas Chemicals convert prothrombin into thrombin Thrombin (enzyme) catalyses soluble fibrinogen into insoluble fibrin Fibrin forms a mesh that traps more platelets & blood cells

8. Coronary Thrombosis

9. Clonal selection & Memory cell formation Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

10. Phagocytic White Blood Cells

11. The Immune Response Early on the immune system cannot differentiate between disease invaders & say, a transplanted kidney – “self” or “not-self” Remember, “not-self” = antigen – Antigens are found on the surface of the pathogens All our body cells have same membrane proteins

12. Response to invaders Body produces antibodies (protein molecules) in response to pathogens They are antigen specific – Either pieces of cell membranes or protein capsids Antibodies are Y-shaped – Binding sites at ends of Y – Where antibody attaches to antigen

13. Antibody production Leucocytes have different types of B lymphocytes Each B cell can synthesize & secrete a specific antibody which binds to a specific antigen You don’t have enough of each type B cell for the amount of secretion that may be needed an one time Leucocytes represent about 1% of all the cells in your bloodstream

14. Antibody production Macrophage encounters an antigen Phagocytosis (partial digestion) Molecular pieces of invader are displayed on the cell membrane (antigen presentation) Leucocytes (helper T- cells) are activated

15. Antibody production Helper T-cells turn the immune response from non-specific to antigen specific as the identity of the antigen is now determined Helper T-cells chemically communicate with (activate) the specific B cell type that can produce antibody needed

16. Cell cloning When Helper T-cell activates a specific B cell, the B cell begins dividing Known as cell cloning – All daughter cells produce same antibody 2 types of cloned B cells Plasma cellsMemory cells

17. 2 types of cloned B cells Antibody-secreting plasma cells Secrete antibodies immediately & help fight off the 1 st (primary) infection Memory cells Cells do not secrete antibodies during the 1 st infection, but are long-lived cells which remain circulating in the bloodstream for secondary infection

19. During the time it takes to activate the system the pathogen is causing damage & producing symptoms Staphylococcus Aureus

20. Subsequent infections Memory cells produced at 1 st infection are floating in bloodstream Long-lived cells, now in large numbers, are capable of responding to the same pathogen very quickly

21. Principles of Immunity Challenge & response: immune system must be challenged by an antigen during the 1 st infection in order to develop immunity Clonal selection: the identification of the leucocytes that can help with a specific pathogen & the multiple cell divisions Memory cells: cells that provide long-term immunity. You must have experienced the pathogen to produce these cells.

22. Blood Typing Lab Blood types are – A, B, AB, O Proteins on the erythrocytes Also look at the Rh factor

23. Define active & passive immunity Active immunity: the events previously described represent active immunity Passive immunity: when an organism acquires antibodies which were produced in another organism – only the organism which produced the antibodies has the memory cells & thus gains full long-term immunity – Therefore – short –term benefits

24. Examples of Passive Immunity Transfer of antibodies from mother to fetus through the placenta. Memory cells aren’t transferred. Acquisition of antibodies from the mother’s colostrum (breast mild produced in late pregnancy and the 1 st few days after birth). Injection of antibodies in antisera (antivenoms produced for treatment of poisonous snake and spider bites.)

25. Explain the principle of vaccination You cannot be immune to a pathogen before being exposed to it Vaccines developed as the 1 st exposure Vaccine composed of weakened pathogen – Select a “weak” strain – Heat the pathogen – Chemically treat the pathogen

26. Vaccines Leucocytes recognize weakened pathogen as “not-self” Primary immune response takes place – Memory B cells made Vaccines don’t prevent infections - secondary immune response is quicker - secondary response is more intense

27. Smallpox Edward Jenner Cowpox vs smallpox Experimented on an 8 year old boy using cowpox & then smallpox Child was immune to smallpox Acceptable today?

28. Discuss the benefits & dangers of vaccination Some diseases have been eliminated (smallpox) – 1977 last reported case Some vaccines are required by the government for entering school – MMR – Polio – DPT

29. BenefitDanger Possible total ellimination of the disease. This has occurred with smallpox & many believe it is possible to eradicate polio & measles Prior to 1999, many vaccines contained thimerosal, a mercury-based preservative. Mercury is a neurotoxin to which infants & young children are particularly susceptible Decrease in spread of epidemics & pandemics. Increased international travel has made this more important than ever. The perception exists that multiple vaccines given to children in a relatively short period of time may ‘overload’ their immune system Preventative medicine is typically the most cost-effective approach to healthcare. Costs associated with vaccination programs are small compared to the costs Anecdotal evidence suggested that MMR vaccine may have a link to the onset of autism. Clinical studies have not supported this. Each vaccinated individual benefits because the full symptoms of the disease do not have to be experienced in order to gain immunity Cases have been reported of vaccines leading to allergic reactions and autoimmune responses

31. Human Immunodeficiency Virus (HIV) Infects key lymphocyte cells in humans Lose the ability to create adequate antibodies – AIDS (Acquired Immune Deficiency Disorder)

32. HIV Why do people die? Because of a lack of antibodies, various infections occur One of these is usually what kills a person Transmission? Unprotected sex Sharing needles Fetus during pregnancy During labor Delivery of the baby Breastfeeding Blood transfusions in other countries Most common

33. Diseases can cross species lines HIV/AIDS Ebola SARS (severe acute respiratory syndrome) H1N1

34. Antibiotics Chemicals that target differences between eukaryotic and prokaryotic cells Block some of the biochemistry Have NO effect on viruses

35. Penicillin Fleming discovered penicillin (1928) – Unable to isolate it from the fungus Chain and Florey – Isolate small amount – Injected 8 mice with deadly bacteria – ½ the mice get penicillin They lived for several days Is that enough data?

36. MRSA – Bacterial resistance Bacterial infection = thousands of cells Reproduce rapidly Great chance for genetic variant Survive antibiotics & create a new strain of bacteria

37. Antibiotic resistance Long-term use of antibiotics Overuse of antibiotics

38. Describe the production of monoclonal antibodies and their use in diagnosis and in treatment.

39. Polyclonal Antibodies A primary immune response = polyclonal response – Pathogen is being recognized as many antigens & not just one – Once a polyclonal immune response has occurred, it is very difficult to separate the different kinds of antibody that have been produced

40. Monoclonal Antibodies Begin with the injection of an antigen into a lab animal (mouse) Mouse is given time to go through primary immune response (polyclonal) Spleen of the mouse is harvested in order to gain access to many blood cells Some of the leucocytes cloned for the antigen will be a part of the cellular population within the spleen

41. Monoclonal Antibodies Mouse injected with a chosen antigen Mouse spleen harvested days later Leucocytes removes Fused with myeloma cells to form hybridoma cells Hybridomas grown in separate cultures ELISA test used to identify cultures secreting desired antibodies Antibody purified from cell culture Antibodies can be uses for variety of diagnostic purposes

42. Monoclonal antibodies Myeloma cells = cancerous cells Hybridoma cells = B cells & myeloma cells fused together Hybridoma cells produce specific antibodies & are very long lived Moved to environment that kills B cells & myeloma cells that didn’t fuse ELISA = enzyme-linked immunosorbent assay

43. Monoclonal antibodies Test for specific antibodies using ELISA ELISA test identifies which containers hold a pure colony of B cells which are producing the type of antibody desired

44. Uses of monoclonal antibodies Embryo produces hormone – human chorionic gonadotrophin (HCG). Shows up in mother’s urine Colour change = pregnancy test Diagnosing pregnancy The monoclonal antibodies could be chemically modified to carry a specific toxin or a pin-point radiation therapy Cancer treatment

45. Allergies Problems with the immune system Allergic response Non-pathogenic substance

46. Allergies 1 st exposure – person produces an antibody called IgE IgE bind to white blood cells called mast cells 2 nd time – IgE antibodies bind to the mast cell releasing large amounts of histamine Histamine causes: