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Immunology: diagnosing infections. What is diagnostic immunology?. Term for a variety of diagnostic techniques that rely on the specificity of the bond between antibodies and antigens Using antibodies to identify pathogens. Uses serological tests.
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What is diagnostic immunology? • Term for a variety of diagnostic techniques that rely on the specificity of the bond between antibodies and antigens • Using antibodies to identify pathogens
Uses serological tests • Direct tests detect antigens (from patient sample). • Indirect tests detect antibodies (in patient′s serum).
What are some serological tests? • Monoclonal antibodies • Many techniques • Precipitation reactions • Agglutination reactions • Complement-fixation reactions • ELISA • fluorescent-antibody • Western blot
What are monoclonal antibodies? • Produced by specialized B cells. • Single type of Ab. • From any substance • Possible to create monoclonal antibodies that specifically bind to that substance • Can serve to • detect or purify that substance • Useful • Uniform • Highly specific • Produced in large quantities
What are monoclonal antibodies? • Immunotoxins: Mabs conjugated • with a toxin to target cancer cells. • Chimeric mabs: Genetically modified mice that produce Ab • with a human constant region. • Humanized mabs: Mabs that are mostly human • except for mouse antigen-binding. • Fully human antibodies: Mabs produced from a human gene • on a mouse.
What are precipitation reactions? • Involve soluble antigens with antibodies. Figure 18.4
What are agglutination reactions? • Involve particulate antigens and antibodies. • Antigens may be • On a cell (direct agglutination). • Attached to latex spheres (indirect or passive agglutination). Figure 18.5
What is direct agglutination? • Antibody titer • Is the concentration of antibodies against a particular antigen. Figure 18.6
What is ELISA? Enzyme-linked immunosorbent assay A positive direct ELISA to detect antigens A positive direct ELSIA to detect antibodies
What is fluorescent-antibody testing? • Tagged antibodies Direct method Indirect method
What is the Western Blot? • Similar to Southern Blot • Proteins, not DNA