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Chap20 Immunology & Serology

Chap20 Immunology & Serology






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    Chap20 Immunology & Serology Chap20 Immunology & Serology Presentation Transcript

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