Applied Immunology Flashcards
Naturally Acquired immunity:
ACTIVE?
Antigens enter the body naturally; body produces antibodies and specialized lymphocytes
Naturally Acquired immunity:
PASSIVE?
Antibodies pass from mother to fetus via placenta or to infant in the mother’s milk.
Artificially Acquired immunity:
ACTIVE?
Active: Antigens are introduced in vaccines; body produces antibodies and specialized lymphocytes
Artificially Acquired immunity:
PASSIVE?
Preformed antibodies in immune serum introduced into body by injection
Two artificial methods of immunity?
Active and passive immunization
Active immunization:
• Administration of antigens so patient actively mounts a protective immune response
Passive immunization:
• Individual acquires immunity through the transfer of antibodies formed by immune individual or animal
History of immunization:
– Chinese noticed children who recovered from smallpox did not contract the disease again
– They infected children with material from a smallpox scab to induce immunity
• This process known as variolation
– Variolation spread to England and America but was stopped because of risk of death
– 1796 – Edward Jenner discovered
cowpox was similar to smallpox
– 1879 – Louis Pasteur developed
a vaccine against Pasteurella multocida
Antibody transfer was developed when it
was discovered that vaccines protected through the action of antibodies
Pastuer’s research:
• Avian cholera (caused by bacteria not virus) was a common zoonotic disease
• Discovered attenuated pathogen accidentally
• Went on to make other vaccinations
Active immunization:
Vaccine types
Attenuated (live) vaccines (weakened)
– Use pathogens with reduced virulence
– Can result in mild infections
– Active microbes stimulate a strong immune response
– Can provide contact immunity
Active immunization:
Vaccine types
• Inactivated vaccines
– Whole-agent vaccines (safer, bacteria is dead)
- Subunit vaccines
Microbes don’t provide many
antigenic molecules to stimulate the immune response
– Often contain adjuvants (additives)
Active Immunization
– Vaccine types
• Toxoid vaccines
– Chemically or thermally modified toxins used to stimulate immunity
– Useful for some bacterial diseases
– Stimulate antibody-mediated immunity
– Require multiple doses because they possess few antigenic determinants (not strong enough=need boosters)
• Active Immunization
– Vaccine types
• Combination vaccines
-Administration of antigens from several pathogens • Vaccines using recombinant gene technology
– Attempts to make vaccines more effective, cheaper, safer
– Variety of techniques used to improve vaccines
• Active Immunization
– Vaccine safety
• Problems associated with immunization:
– Mild toxicity most common
– Risk of anaphylactic shock
– Residual virulence from attenuated viruses
– Allegations that certain vaccines cause autism, diabetes, and asthma
» Research has not substantiated these allegations
• Passive Immunotherapy
Administration of antiserum containing:
Preformed antibodies
Passive immunotherapy:
Immediate protection against
recent infection or ongoing disease
Passive immunotherapy:
Antisera have several limitations
• Contain antibodies against many antigens
• Can trigger allergic reactions called serum sickness
• Viral pathogens may contaminate antisera
• Antibodies of antisera are degraded relatively quickly
-limitations are overcome through development of hybridomas
What is hybidoma?
Myeloma cells fused with plasma cells that make the antibodies
Immune testing: serology
Antibody-Antigen Immune Testing: Study and diagnostic use of antigen antibody interactions in blood serum
Two categories of immune testing
– Direct testing
• Looking for presence of antigens
– Indirect testing
• Look for antibodies that have formed against antigens
What determines which test is chosen? Direct vs indirect?
Test is chosen based on the suspected diagnosis, cost, and speed with which a result can be obtained
Precipitate reactions:
Involve soluble antigens with antibodies
Agglutination Reactions
Involve:
particulate antigens and antibodies
Antigens may be:
– On a cell (direct agglutination)
– Attached to latex spheres (indirect or passive agglutination)
Negative means no antigen on RBC
• Agglutination occurs due to the
cross-linking of antibodies with particulate antigens
Agglutination is the
clumping of insoluble particles, whereas precipitation involves the aggregation of soluble molecules
These reactions are easy to see and interpret with the unaided eye
Hemagglutination:
the agglutination of RBC, can be used to determine blood type
Hemagglutination involves
agglutination of RBCs.
Viral hemagglutination inhibition tests for:
antibodies by the antibodies’ ability to inhibit the agglutination (clumping) of red blood cells by the viral hemagglutinin.
Neutralization reactions:
Eliminate the harmful effect of a virus or exotoxin
Labeled antibody tests:
– Uses antibody molecules linked to some “label” that enables them to be easily detected
– Used to detect either antigens or antibodies
Labeled Antibody Tests
• The Complement Fixation Test
– Based on generation of membrane attack complexes during complement activation
– Detect presence of specific antibodies in an individual’s serum
– Can detect antibody amounts too small to detect by agglutination
Labeled Antibody Tests
– Fluorescent antibody tests
• Use fluorescent dyes as labels
• Fluorescein is one dye used in these tests
• Fluorescein-labeled antibodies used in two types of tests
–Direct fluorescent antibody tests
–Indirect fluorescent antibody tests
Labeled Antibody Test
– ELISA
• Stands for enzyme-linked immunosorbent assay • Uses an enzyme as the label
– Reaction of enzyme with its substrate produces colored product
• Commonly used to detect presence of antibodies in serum
Labeled Antibody Test – ELISA
• Antibody sandwich ELISA
– Modification of the ELISA technique
– Commonly used to detect _________
– It is “sandwiched” between two antibody molecules
Labeled Antibody Test
– ELISA
• Advantages of the ELISA
– Can detect either antibody or antigen
– Can quantify amounts of antigen or antibody
– Easy to perform and can test many samples quickly
– Plates coated with antigen and gelatin can be stored for later testing
Labeled Antibody Test
• Western blot test
– Technique to detect antibodies against multiple antigens
– Advantages over other tests
– Can detect more types of antibodies – Less subject to misinterpretation
Recent Developments in Antibody- Antigen Immune Testing
(COVID & pregnancy tests)
– Simple immunoassays that give results in minutes
– Useful in determining a preliminary diagnosis
– Immunofiltration and immunochromatography are most common
• Recent Developments in Antibody- Antigen Immune Testing
-immunofiltration:
• Rapid ELISA that uses antibodies bound to membrane filters rather than polystyrene plates
– Membrane filters have large surface area
» Assay quicker to complete
Recent Developments in Immune Testing
– Immunochromatography
• Very rapid and easy-to-read ELISAs
• Antigen solution flows through a porous strip and encounters labeled antibody
• Visible line produced when antigen-antibody immune complexes encounter antibody against them
• Used for pregnancy testing and rapid identification of infectious agents
Serological Tests
Precipitation:
Soluble antigens
Serological Tests
Agglutination:
Particular antigens
Serological Tests
Hemagglutination:
Agglutination of RBCs
Serological Tests
Fluorescent-antibody technique:
Antibodies linked to fluorescent dye
Serological Tests
Complement fixation:
RBCs are indicator
Serological Tests
Neutralization:
Inactivates toxin or virus
Serological Tests
ELISA:
enzyme/substrate complex is the indicator
