Immune System Notes

1. Non-specific (p. 174 N)
   1. skin and other first line defenses (p. 852 C)
      1. physical barrier
      2. cells shed so microbes can't colonize
      3. oil and sweat have pH 3-5 to discourage microbes
      4. saliva - lysozyme to digest bacterial cell wall
      5. tears - lysozyme
      6. mucous (yummy) - to trap microbes and airborne pathogens (especially in respiratory tract)
      7. stomach - low pH
   2. White Blood Cells (WBC)
      1. engulf invaders - phagocytes (p. 853 C)
      2. glycoproteins as cell labels
      3. macrophages (p. 854 C)
   3. Antimicrobial proteins (p. 854 C)
      1. complement (so-called because complements other arms of immune system)
         1. about 20 different proteins in inactive form
         2. make membrane attack complex
         3. attract macrophages
      2. interferons
         1. secreted by cells infected by virus
         2. cause neighboring cells to produce protein which interfere with viral replication
   4. Inflammatory Response (p. 855 C)
      1. Local injury or infection
         1. vasodilation near injury or infection increases blood causing redness and heat
         2. dilated blood vessels more permeable to fluids - edema
         3. increased blood flow brings more WBC
         4. some WBC release histamine when injured
         5. histamine causes local vasodilation
      2. more widespread infection
         1. some WBC release pyrogens which set the body thermostat higher - fever
         2. inhibits bacterial growth
         3. speeds phagocytosis and repair
2. Specific - depends on two classes of lymphocytes, both produced in the bone marrow; cells mature in bone marrow and T cells mature in thymus
   1. Humoral - depends on B cells (p. 176 N, p. 858 C)
      1. each cell is specific for one antigen (ag)
      2. when meet the ag, become activated and divide to form many clones
      3. the clones produce antibodies (ab) for 4-5 days before dying
   2. Cell - mediated (depends on T cells) (p. 178 N, p. 867 C)
      1. T cells don't recognize free ag
      2. when macrophage devours microbe, displays ag on membrane
      3. Helper T (T_H) cells recognize ag on macrophage, becomes activated and divides rapidly producing clones
      4. clones secrete interleukin which activates (or helps) other T and B cells
      5. Killer T (cytotoxic T or T_C) cells are also activated
      6. T_C recognize your own cells that are displaying ag or unusual markers (e.g., cancer, organ transplants) and destroy them
      7. any viruses released by this process dealt with by humoral immunity
      8. Suppressor T (T_S) cells turn off immune response but not well understood
      9. Memory T cells are long-lived and respond faster to second exposure
3. Immune Disorders
   1. Allergies
      1. over-reaction to a harmless substance
      2. response is caused by histamine
         1. tissue swelling
         2. excess mucous (yum)
         3. constricted airway
         4. sneezing
         5. tears
   2. Lupus - immune response to your own cells parts (especially nucleic acids)
   3. rheumatoid arthritis - immune response to joint cartilage
   4. insulin-dependant diabetes - attack the insulin producing cells of pancreas
   5. multiple sclerosis - attack myelin sheath
   6. AIDS
      1. HIV attacks T_H cells
      2. some cells are killed by immune system but others produce more virus
      3. immune system slowly loses
4. Vaccines
   1. inactivated bacteria or virus or some other ag
   2. provokes immune response but not the disease or illness
   3. memory cells react faster to second exposure
   4. some pathogens mutate too quickly to be eliminated by vaccines