Transcript Kuby Immunology 6/e

Chapter 6
Antigen-Antibody Interactions
Dr. Capers
Kindt • Goldsby • Osborne
Kuby IMMUNOLOGY
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
Cross-reactivity

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
antigens

Immunoassays –
measuring Ag-Ab
interactions
 Vital roles:
○ Diagnosing disease
○ Monitoring level of
humoral response
○ Identifying molecules
of biological or
medical interest
Precipitation Reactions

Ag-Ab interactions can form visible
precipitate
 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
ELISA

Enzyme-Linked Immunosorbent Assay
○ Examples:
 Indirect ELISA
 Sandwich ELISA
 Competitive ELISA
Indirect ELISA

Used to determine if a particular
antibody is present
Immunoprecipitation

Using microscopic magnetic beads
○ Below is cell with magnetic beads attached
Immunofluorescence

Using
Immunofluorescence to
see the effect of cancer
treatments
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