Chap20 Immunology & Serology


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Chap20 Immunology & Serology

  1. 1. Immunity and Serology Chapter 20
  2. 2. <ul><li>Immunity is a condition under which an individual is protected from the disease </li></ul><ul><li>Two general types of immunity </li></ul><ul><ul><li>Innate Immunity </li></ul></ul><ul><ul><li>Acquired Immunity </li></ul></ul><ul><li>Types of Acquired Immunity </li></ul><ul><ul><li>ACTIVE IMMUNITY </li></ul></ul><ul><ul><ul><li>Naturally Acquired Active Immunity </li></ul></ul></ul><ul><ul><ul><li>Artificially Acquired Active Immunity </li></ul></ul></ul><ul><ul><li>PASSIVE IMMUNITY </li></ul></ul><ul><ul><ul><li>Naturally Acquired Passive Immunity </li></ul></ul></ul><ul><ul><ul><li>Artificially Acquired Passive Immunity </li></ul></ul></ul>Immunity to Disease
  3. 3. 4 Types of Acquired Immunity
  4. 4. <ul><li>Naturally acquired active immunity develops from exposure to an infectious agent </li></ul><ul><ul><li>Active immunity occurs when the body’s immune system responds to antigens by producing antibodies and lymphocytes </li></ul></ul><ul><ul><li>Naturally acquired active immunity follows illness or pathogen exposure </li></ul></ul><ul><li>Artificially acquired active immunity occurs through vaccination </li></ul><ul><ul><li>Vaccines contain treated or altered microbes, toxins, or parts of microbes </li></ul></ul><ul><ul><ul><li>a primary immune response occurs </li></ul></ul></ul><ul><ul><ul><li>memory cells are formed </li></ul></ul></ul><ul><ul><ul><li>the person does not usually become ill </li></ul></ul></ul>Active Immunity
  5. 5. <ul><li>Live, attenuated vaccines contain weakened microbes that multiply at only low levels, inducing a strong immune response </li></ul><ul><ul><li>Organisms can revert to a virulent form and cause disease </li></ul></ul><ul><ul><li>A single-dose vaccine can combine vaccines for different diseases </li></ul></ul><ul><ul><li>Vaccines using attenuated bacteria are difficult and not widely used </li></ul></ul>Types of Vaccines
  6. 6. <ul><li>Inactivated vaccines contain killed pathogens, which induce a weaker immune response </li></ul><ul><ul><li>Booster shots are required to maintain immunity </li></ul></ul><ul><ul><li>They are safer than attenuated vaccines because they cannot cause disease </li></ul></ul><ul><li>Toxoid vaccines contain inactivated toxins (toxoids) </li></ul><ul><ul><li>Since the product is inactivated, booster shots are required </li></ul></ul><ul><ul><li>Prepared by incubating toxins with a chemical </li></ul></ul><ul><li>*to avoid multiple injections, vaccines are combined into single-dose vaccine </li></ul>Types of Vaccines
  7. 7. <ul><li>Subunit vaccines contain only those parts of the antigens that stimulate a strong immune response </li></ul><ul><ul><li>Recombinant DNA technology can be used to create recombinant subunit vaccines </li></ul></ul><ul><ul><li>Subunits cannot cause disease </li></ul></ul><ul><li>Conjugate vaccines are created by attaching bacterial capsule polysaccharides to a toxoid </li></ul><ul><ul><li>They elicit a strong immune response </li></ul></ul>Types of Vaccines
  8. 8. <ul><li>DNA vaccines depend on the ability of some cells to: </li></ul><ul><ul><ul><li>take up and translate foreign DNA </li></ul></ul></ul><ul><ul><ul><li>display the resulting proteins, inducing a strong immune response </li></ul></ul></ul><ul><ul><li>Naked DNA vaccines contain engineered plasmids that contain a gene from a pathogen </li></ul></ul><ul><ul><li>They are not infective or replicative, so cannot cause disease </li></ul></ul><ul><li>Recombinant vector vaccines involve DNA incorporated into an attenuated pathogen </li></ul><ul><ul><li>The pathogen: </li></ul></ul><ul><ul><ul><li>takes the DNA into the cells (viral vector) or </li></ul></ul></ul><ul><ul><ul><li>incorporates the DNA and present antigens (bacterial vector) </li></ul></ul></ul><ul><li>*Adjuvants : increase efficacy of a vaccine or toxoid by increasing availability of the antigen in the lymphatic system. = stimulate phagocytic activity, IL 1 activation, sustained immune response </li></ul>Types of Vaccines
  9. 9. Childhood and Adolescent Immunization Schedule - 2006
  10. 10. <ul><li>Passive Immunity develops when antibodies enter the body from outside source </li></ul><ul><li>Two Types: NATURAL OR ARTIFICIAL </li></ul><ul><li>Naturally acquired passive immunity (congenital immunity) occurs when antibodies pass from mother to fetus </li></ul><ul><ul><li>Maternal IgG antibodies remain in the child 3-6 months after birth </li></ul></ul><ul><ul><li>Maternal antibodies also pass to the newborn through: </li></ul></ul><ul><ul><ul><li>first milk (colostrum) </li></ul></ul></ul><ul><ul><ul><li>breast milk </li></ul></ul></ul>Passive Immunity
  11. 11. <ul><li>Artificially acquired passive immunity involves injection of antibody-rich serum into a body </li></ul><ul><ul><li>The serum can be used to: </li></ul></ul><ul><ul><ul><li>prevent disease (prophylactic) </li></ul></ul></ul><ul><ul><ul><li>treat disease (therapeutic serum) </li></ul></ul></ul><ul><ul><li>Antiserum: hyperimmune serum or convalescent serum </li></ul></ul><ul><li>The immune system may recognize foreign serum proteins as “nonself” and mount an allergic reaction </li></ul><ul><ul><li>Immune complexes may form and serum sickness may develop </li></ul></ul>Passive Immunity
  12. 12. <ul><li>In herd immunity, the majority of a population are immune </li></ul><ul><li>Unvaccinated individuals are unlikely to contact an infected individual </li></ul><ul><li>Herd immunity is affected by: </li></ul><ul><ul><li>population density </li></ul></ul><ul><ul><li>the strength of a person’s immune system </li></ul></ul>Herd Immunity
  13. 13. <ul><li>People with egg allergies should not take flu vaccinations </li></ul><ul><li>The risk of contracting a disease is much greater than any risk associated with vaccines </li></ul><ul><li>Thimerosal </li></ul>Do vaccines have dangerous side effects?
  14. 14. <ul><li>Serology: branch of immunology that studies serological reactions </li></ul><ul><li>Serological reactions can help diagnose microbial infections </li></ul><ul><li>Ag-Ab reactions are studied under laboratory conditions </li></ul><ul><li>Uses patient’s serum </li></ul><ul><li>Function: confirmatory test, detect organism in tissue, aid MD in following course of disease and determine immune states </li></ul>Serological Reactions
  15. 15. <ul><li>Titration is the dilution of antigen or antibody solution to the most favorable concentration </li></ul><ul><li>The titer is the most dilute concentration of serum antibody that reacts to its antigen </li></ul><ul><ul><li>A rise in the titer ratio (antibody:serum) indicates disease </li></ul></ul>Serological Reactions
  16. 16. <ul><li>Neutralization Involves Antigen-Antibody Reactions </li></ul><ul><ul><li>Neutralization is used to identify toxins and antitoxins, viruses and viral antibodies </li></ul></ul><ul><ul><li>If a specific agent is suspected, to determine if the toxin has been neutralized, a sample can be: </li></ul></ul><ul><ul><ul><li>mixed with an antitoxin </li></ul></ul></ul><ul><ul><ul><li>injected into a lab animal </li></ul></ul></ul><ul><ul><ul><li>Example: detection of botulinum toxin in food </li></ul></ul></ul><ul><ul><li>The Schick test is used to determine if a person is immune to diphtheria (intradermal test) </li></ul></ul>Serological Reactions
  17. 17. <ul><li>Precipitation reactions involve antigens and antibodies cross-linked in a huge lattice </li></ul><ul><li>In fluid, the molecules diffuse until they reach the ideal concentration (the zone of equivalence) </li></ul><ul><li>In immunodiffusion, antigens and antibodies diffuse through a gel until they reach the zone of equivalence </li></ul><ul><ul><li>Oudin tube technique </li></ul></ul><ul><ul><li>Ouchterlony plate technique </li></ul></ul>Serological Reactions
  18. 18. <ul><li>In immunoelectrophoresis, diffusion is combined with electrophoresis </li></ul>Serological Reactions
  19. 19. <ul><li>Agglutination – antibodies interact with antigens on a surface of a particular object and cause object to clump together. </li></ul><ul><li>A visible reaction requires less antibody or antigen if they are clumped together </li></ul><ul><li>In passive agglutination: </li></ul><ul><ul><li>antigens are adsorbed onto a surface </li></ul></ul><ul><ul><li>antibodies are added </li></ul></ul><ul><ul><li>agglutination is observed </li></ul></ul>Serological Reactions
  20. 20. <ul><li>Hemagglutination is used to: </li></ul><ul><ul><li>determine blood type </li></ul></ul><ul><ul><li>Detect viruses that cause agglutination of red blood cells </li></ul></ul><ul><li>Flocculation : precipitation and agglutination; Ag exists in a non-cellular particulate form that reacts with antibodies to yield large, visible aggregates. </li></ul>Serological Reactions
  21. 21. <ul><li>Complement Fixation Can Detect Antibodies to a Variety of Pathogens </li></ul>Serological Reactions
  22. 22. <ul><li>Labeling Methods Are Used to Detect Antigen-Antibody Binding </li></ul><ul><ul><li>A fluorescent antibody technique can detect antigen-antibody binding by labeling antibodies with a fluorescent marker </li></ul></ul><ul><ul><li>Can be direct or indirect (FTA-ABS) </li></ul></ul>Serological Reactions
  23. 23. <ul><li>The radioimmunoassay (RIA) is extremely sensitive, using radioactivity-labeled antigens; based on the competition between radioactive labeled Ag and unlabeled Ag for the reactive sites on Ab molecule </li></ul><ul><li>The radioallergosorbent test (RAST) uses radioactive antiglobulin antibodies </li></ul>Serological Reactions
  24. 24. <ul><li>The enzyme-linked immunosorbent assay (ELISA) is similar to RAST </li></ul><ul><ul><li>It uses an enzyme system instead of radioactivity (horseradish peroxidase) </li></ul></ul><ul><ul><li>It is often used to detect antibodies against HIV </li></ul></ul>Serological Reactions
  25. 25. <ul><li>Monoclonal Antibodies Are Becoming a “Magic Bullet” in Biomedicine </li></ul><ul><ul><li>Polyclonal antibodies occur because there are multiple epitopes on a pathogen </li></ul></ul><ul><ul><ul><li>They activate different B cell populations </li></ul></ul></ul>
  26. 26. <ul><li>In the lab, antibodies recognizing one epitope (monoclonal antibodies [mAb]) are produced using myelomas </li></ul><ul><li>Myeloma cells are fused to and activated B cell to form a hybridoma </li></ul><ul><li>A hybridoma producing the desired mAb can be cloned </li></ul><ul><li>MAbs can be used in: </li></ul><ul><ul><li>disease prevention </li></ul></ul><ul><ul><li>immunomodulation (controlling overactive inflammatory responses) </li></ul></ul>
  27. 27. <ul><li>Gene Probes Are Single-Stranded DNA segments </li></ul><ul><ul><li>They hunt down complementary DNA fragment and emit a signal </li></ul></ul><ul><ul><li>The polymerase chain reaction (PCR) is used to increase the amount of DNA to be searched </li></ul></ul><ul><ul><li>Gene probes and PCR are use in: </li></ul></ul><ul><ul><ul><li>HIV and HPV detection </li></ul></ul></ul><ul><ul><ul><li>water-quality tests </li></ul></ul></ul>