Defense against infectious disease

1. Defense against infectious disease Part 2 – Chapter 11.1

2. 11.1.1 Describe the process of blood clotting. • Damaged blood vessel released chemicals • Chemicals stimulate platelets to adhere to damaged area • Platelets release clotting factors • clotting factors convert prothrombin into thrombin • Thrombin is an enzyme that converts fibrinogen into fibrin • Fibrin forms a mesh to stabilize platelet plug • Clot forms

3. 11.1.2 Outline the principle of challenge and response, clonal selection, and memory cells as the basis of immunity. • Immunity: Increased resistance to a pathogen • Challenge: Invasion of an organism by pathogens • Response: Non-specific and specific actions taken by the immune system • Clonal Selection: antigen-driven cloning of lymphocytes • cloning of lymphocytes because of exposure to antigens • each receptor binds a particular antigen, so only a small portion of the lymphocytes are turned ‘on’ • this causes the ‘on’ cells to be cloned, all of which recognize the invader

4. 11.1.2 Outline the principle of challenge and response, clonal selection, and memory cells as the basis of immunity. • Effector cells: Short-lived cells that combat the same antigen • Memory cells: As a result of the activation of B and T cells (some of which differentiate to be effector cells), some become cells that are saved for later and will quickly recognize the antigen

5. Describe the cellular basis for immunological memory. • Memory = Recognition of a previously encountered antigen • based on memory cells which are produced during clonal selection during primary immune response • Memory cells are not active during the primary response and survive in the system for a long time • When the same antigen that caused a primary response again enters the body, the memory cells are activated and rapidly proliferate to form a new clone of effector cells and memory cells

6. 11.1.3 Define active and passive immunity. • Active Immunity • Immunity due to production of antibodies by the organism itself after the body’s defense mechanisms have been stimulated by invasion of foreign microorganisms (ex: chicken pox) • Can also be acquired by immunization (vaccination) • Passive Immunity • Immunity due to acquisition of antibodies from another organism in which active immunity has been stimulated • Naturally during pregnancy when mom passes antibodies to fetus • Antibodies are passed during nursing • Can also be passed from one animal to another if one animal has the antibodies and another is injected with the antibodies

7. 11.1.4 Explain antibody production. • Specific antigen type is identified • Specific B lymphocyte binds to antigen • B lymphocytes clone themselves to rapidly increase their numbers • B lymphocytes begin antibody production • Antibodies circulate bloodstream to find antigen match • Antibodies help eliminate the pathogen • Some cloned B lymphocytes remain in bloodstream & give immunity from a 2nd infection by same pathogen = memory cells

8. 11.1.5 Describe the production of monoclonal antibodies and their use in diagnosis and in treatment. Monoclonal Antibodies • A mouse is immunized to antigen X to stimulate the production of antibodies targeted against X. Cells are isolated from the mouse's spleen. • These are ‘polyclonal’ antibodies because they are a mixture from all sorts of antigens or parts of antigens • Monoclonal antibodies are produced by fusing single antibody-forming cells to tumor cells grown in culture. The resulting cell is called a hybridoma. Binding with a tumor cell gives the hybridoma unlimited life. • Each individual hybridoma makes large quantities of identical antibody molecules. Scientists can produce cell lines that produce single (monoclonal) antibodies because they come from one single original cell.

9. 11.1.5 Describe the production of monoclonal antibodies and their use in diagnosis and in treatment. Uses in Diagnoses: • Detection of Human Chorionic Gonadotropin (hCG) in pregnancy test kits Uses in Treatment: • Targeting of cancer cells with drugs attached to B’s

11. 11.1.6 Explain the principle of vaccination. Vaccine: a weakened or dead pathogen or part of a pathogen • Some have inactivated toxins from bacteria • Given by a shot or liquid by mouth. • An alternative needle-free route: inhalation by aerosol and powder. • The body makes antibodies against the weakened or dead pathogen in the vaccine and also makes memory cells (this is KEY). • Memory cells can be activated when the body encounters the disease again and will quickly clone and proliferate so the animal does not become seriously ill. • Check out: http://www.cdc.gov/nip/

12. 11.1.7 Discuss the benefits and dangers of vaccination. Benefits: • Animal remembers pathogen and will not get as sick later (may prevent death and disabilities, e.g. polio) • Protects general population from disease Danger: • Could cause an over-reaction and kill patient (very rare) • Could inject the incorrect strain of virus and person gets sick anyway (more common than above) • Person could be allergic to shot