1. Chapter 6 Antigen-Antibody Interactions Dr. Capers
immunology

2. Kindt • Goldsby • Osborne
Kuby IMMUNOLOGY
Sixth Edition
Chapter 6
Antigen-Antibody Interactions: Principles and Applications
Copyright © 2007 by W. H. Freeman and Company

3. Antigen-Antibody (Ag-Ab) Interaction
Similar to enzyme-substrate interaction
However, does not lead to irreversible chemical alteration in either the antibody or antigen

4. Noncovalent Interactions
Hydrogen bonds
Ionic bonds
Hydrophobic reactions
Van der Waals
All weak so need combination of all of them to make strong interaction

5. 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

6. Immunoassays – measuring Ag-Ab interactions
Vital roles:
Diagnosing disease
Monitoring level of humoral response
Identifying molecules of biological or medical interest

7. Precipitation Reactions
Ag-Ab interactions can form visible precipitate
Examples:
Radial immunodiffusion
Double immunodiffusion
immunoelectrophoresis

8. In this example, Anti-dog IgG is
Mixed in agar so only what is
Placed in wells (Ag) diffuses out

9. In this example, both antibody and antigen diffuse
Out of wells

10. 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

11. 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

12. ELISA Enzyme-Linked Immunosorbent Assay Examples: Indirect ELISA
Sandwich ELISA
Competitive ELISA

13. Indirect ELISA
Used to determine if a particular antibody is present

17. Immunoprecipitation Using microscopic magnetic beads
Below is cell with magnetic beads attached

19. Immunofluorescence

20. 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)

21. Flow Cytometry
Can provide quantitative data