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Antigen -Antibody Interactions
Precipitin Reactions
Hugh B. Fackrell
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Antigen-Antibody Interactions
Assigned Reading
 Content Outline
 Performance Ojectives

 Key
terms
 Key Concepts

Short Answer Questions
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Assigned Reading
Chapter: 6 pp 144-164
 Janis Kuby’s Immunology 3rd Ed

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Content Outline
Strength of Antigen-Antibody Interactions
 Cross Reactivity
 Precipitin Reactions
 Agglutination Reactions

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Strength of Antigen-Antibody
Interactions
affinity
 avidity

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Cross reactivity
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Mammoth
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Precipitin Reactions
reactions in fluids
 reaction in gels
 radial immunodiffusion
 Ouchterlony
 immunoelectrophoresis

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Ring Test
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Ring Test: Controls
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C reactive Protein ring test
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QPT
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QPT: Zones
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QPT:# Epitopes
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QPT: Simple system
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QPT: Multiple Interactions
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QPT: Multiple Reactions
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Radial Immuno Diffusion
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Double Immuno Diffusion
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Immunodiffusion:
Single reactions
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Immunoelectrophoresis
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Counter Immuno Electrophoresis
Fig 12-7 Barrett 1988
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IEF: Concept
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IEF: IgG IgM IgA
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IEF: Partial Identity
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IEF: Human Serum
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Rocket Immunoelectrophoresis
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Rocket Immunoelectrophoresis 2
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Rocket Immunoelectrophoresis 3
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Agglutination Reactions
hemagglutination
 bacterial agglutination
 passive agglutination
 agglutination inhibition

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Hemagglutination
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The End
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Performance Objectives
Key terms, concepts
short answers
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Key Terms
agglutination, direct agglutination reaction, indirect
agglutination reaction
 antibody affinity, antiserum, association constant
(K), average affinity,
 average intrinsic association constant(Ka), avidity,
ELISA, equilibrium constant,
 equilibrium dialysis, fluorescein, fluorochromes,
hemagglutination,

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passive hemagglutination, passive
hemagglutination inhibition,
 reverse passive hemagglutination, immune
precipitation, immunoelectrophoresis
 immunofluorescence, Indirect fluorecent
antibody test, ring test,

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Ouchterlony methods, plasma, primary
antigen-antibody interactions,
Radioimmunoassay(RIA
 Rhodamine, secondary antigen-antibody
interactions, serology,
 serum, titer, zone phenomena (antibody
excess, antigen excess, equivalence)
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Key Concepts
Explain a primary antigen-antibody interaction
and include at least three important
characteristics.
 Describe the forces that encourage primary
antigen-Antibody interactions
 Assess the reasons for using the different gel
preciptitin reactions
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Distinguish betweeen antibody affinity and
avidity.
 Describe the strength of the primary
antigen-antibody interactions using
equilibrium dialysis. Include the terms K
and Ka
 Compare and contrast RIA and ELISA
 Describe direct and indirect fluorescent
antibody methods.
 Explain zone phenomena.
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Describe a secondary antigen-antibody
interaction in terms of lattice formation and
antigen:antibody ratios.
 Construct a table to compare the various
procedures used to determine the presence of
soluble antigen or antibody in a fluid and in a
gel.
 Distinguish between agglutination and
preciptin reactions and give the advantages
and disadvantages of each.

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Short Answer Questions
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Cross reactivity of antibodies creates
problems for their application in serology.
Explain.
 Differentiate between a primary and a
secondary antigen-antibody reaction.
 What are three important characteristics that
distinguish the two reactions?
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What kinds of noncovalent interactions are
important in antigen-antibody interactions?
What aspect of these interactions is most
important and why?
 How is equilibrium dialysis used to measure
PRIMARY antigen-antibody reactions?
 Differentiate between avidity and affinity.
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Discuss the term lattice formation.
 What are the pros and cons of RIA?
 Describe two types of immunofluorescence
tests.
 What is the advantages of the indirect
procedure over the direct procedure?
 What are some commonly used fluors?

 What

colour does each fluor emit?
What makes precipitin reactions visible?
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What two factors are important in the
development of precipitin reactions?
 Three patterns can be observed in the
Ouchterlony test. DRAW and LABEL
diagrams to illustrate these patterns. What does
each pattern show?
 What is the major advantage of
immunoelectrophoresis over immunodiffusion?
 What are the disadvantages?

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How does agglutination differ from
precipitation?
 Why are agglutinatin tests more sensitive that
precipitin tests?
 Differentiate between direct and indirect
agglutination reactions?
 What is a major advantage of indirect
agglutination reaction over direct reactions?
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Ouchterlony
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Ouchterlony:Partial Identity
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