Kuby Immunology 6/e

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Transcript Kuby Immunology 6/e

Chapter 6
Antigen-Antibody Interactions
Dr. Capers
Kindt • Goldsby • Osborne
Sixth Edition
Chapter 6
Antigen-Antibody Interactions:
Principles and Applications
Copyright © 2007 by W. H. Freeman and Company
Antigen-Antibody (Ag-Ab) Interaction
 Similar to enzyme-substrate interaction
 However, does not lead to irreversible chemical
alteration in either the antibody or antigen
Noncovalent Interactions
 Hydrogen bonds
 Ionic bonds
 Hydrophobic reactions
 Van der Waals
 All weak so need
combination of all
of them to make
strong interaction
Mechanisms of tolerance prevent formation of Abs
against one’s own blood group antigens
○ However, exposure to microbial antigens on
intestinal bacteria induce formation of Abs,
these antigens share similarity to blood group
Immunoassays –
measuring Ag-Ab
 Vital roles:
○ Diagnosing disease
○ Monitoring level of
humoral response
○ Identifying molecules
of biological or
medical interest
Precipitation Reactions
Ag-Ab interactions can form visible
 Examples:
○ Radial immunodiffusion
○ Double immunodiffusion
○ immunoelectrophoresis
In this example, Anti-dog IgG is
Mixed in agar so only what is
Placed in wells (Ag) diffuses out
In this example, both antibody and antigen diffuse
Out of wells
Immunoelectrophoresis –
Antigen is 1st put into wells,
charge is applied to separate
components of antigen mixture,
then troughs are cut and antibody
is allowed to diffuse
through gel
Agglutination Reactions
Visible clumping – agglutination
○ Examples:
 Hemagglutination
 Bacterial Agglutination
Important in all tests for Antibody to be in right concentation
○ Too much antibody will cause univalent binding, need
multivalent for preciptitate or agglutination to occur
Enzyme-Linked Immunosorbent Assay
○ Examples:
 Indirect ELISA
 Sandwich ELISA
 Competitive ELISA
Indirect ELISA
Used to determine if a particular
antibody is present
Using microscopic magnetic beads
○ Below is cell with magnetic beads attached
Immunofluorescence to
see the effect of cancer
E. decrease beta-tubulin
III (found in developing
neurons, if found in other
tissue it can be used as
cancer marker)
 F. decrease thymidilate
kinase (needed by tumor
cell to repair DNA)
Flow Cytometry
Can provide
quantitative data