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Chapter 6 Ag-Ab Interactions. Nature of the Ag-Ab interaction Immunological assays. 4 types of noncovalent forces. Affinity The strength of the total noncovalent interactions between a single Ag-binding site on an Ab and a single epitope is the affinity of the Ab for that epitope.
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Nature of the Ag-Ab interaction Immunological assays
Affinity The strength of the total noncovalent interactions between a single Ag-binding site on an Ab and a single epitope is the affinity of the Ab for that epitope. Avidity The strength of multiple interactions between a multivalent Ab and Ag is called the avidity. Example: secreted pentameric IgM often has a lower affinity than IgG, but the high avidity of IgM, resulting from its higher valence, enables it to bind Ag effectively.
Immunological Assays 1. Precipitation 2. Agglutination 3. Radioimmunoassay 4. Enzyme-linked Immunosorbent Assay 5. Western Blotting 6. Immunofluorescence 7. Flow Cytometry and Fluorescence 8. Immunoelectron Microscopy
Precipitation Reactions: Precipitation in fluids Precipitation in gels - radial immunodiffusion (Mancini method) - double immunodiffusion (Ouchterlony method) Immunoelectrophoresis
Lattice Formation (格子)
Double Immunodiffusion (Ouchterlony method)
Agglutination Reactions: Hemagglutination Bacterial Agglutination Passive Agglutination Agglutination Inhibition
Hemagglutination Agglutination No Agglutination No Ab
Enzyme-linked Immunosorbent Assay (ELISA): - Indirect ELISA - Sandwich ELISA - Competitive ELISA - Chemiluminescence
Flow Cytometry FACS: Fluoresence-activated Cell sorter