Ch 18 - Lab Analysis of the Immune Response Flashcards
Diagnostic Immunology
- Use antibodies as very, very specific test indicators for antigens
- Use antigens as very, very specific test indicators for antibodies
Antigens
Substances that cause the production of antibodies. Usually, components of invading microbes or foreign substances.
Tests in Diagnostic Immunology
Precipitation Reactions, Agglutination Reactions, Neutralization Reactions, Complement-fixation Reactions, Fluorescent Antibody Tests, Enzyme-Linked Immunosorbent Assay (ELISA)
2 Factors for a good diagnostic test
- Test Sensitivity
2. Test Specificity
2 Factors for a good diagnostic test
Test Seneitivity
Probability that the test is reactive if the specimen is a true positive (low false negative %)
2 factors for a good diagnostic test
Test Specificity
Probability that a positive test will not be reactive if a specimen is a true negative (low false positive)
Properties of Immunologic-based Diagnostic Tests
- Interactions of antibodies with antigens
- Known antibody can identify an unknown pathogen
- Known pathogen can identify an unknown antibody
Antigen-Antibody Binding
4 protein chains form a Y shape
- two identical light and 2 heavy chains joined by disulfide bonds
- variable (v) regions are at the ends of the arms; bind epitopes
- constant (Fc) region is identical for a particular Ig class
Monoclonal Antibodies
Hybridoma
“immortal” cancerous B cell (myeloma) combined with an antibody-producing normal B cell. Produces monoclonal antibodies (mAb)
Monoclonal Antibodies
Uniform, highly specific for 1 antigen, and produced in large quantities. Uses: diagnostic tools and human therapy. Often derived from mouse cells leading to some side effects
Precipitation Reactions
Precipitin
Visible antigen-antibody complex
Precipitation Reactions
Precipitin Ring
Oprimal amount of antibody in a test
Precipitin
Soluble antigens binding to antibodies to form visible aggregates
Precipitin Ring Test
Uses liquid in a narrow test tube for precipitin formation. A cloudy line forms where there is the optimal ratio of antigen and antibody.
Immunodiffusion Test
Uses agar as the medium for precipitin formation. Precipitation reactions carried out in an agar gel medium. Precipitin develops at the point where the optimal antigen-antibody ration occurs during diffusion through the gel.
