Flashcards in Antibodies as diagnostic tools Deck (14):
What can you attach to the ends of antibodies?
Enzymes e.g. peroxidase
Fluorescent probes e.g. dyes
Magnetic beads e.g. purification of cell types
Drugs e.g. Kadcyla, anti-HER2
What is the basis for many diagnostic tests that involve antibodies?
Unique specificity of antibodies to antigens
What are the two types of antibodies?
Produced by the patient
Manufactured - antisera from immunised animals, monoclonal
How are monoclonal antibodies generated?
mouse challenged with antigen
Spleen cell removed that produce the Ab - limited cell division so fused with myeloma cells - forming Hybridomas
Then culture in HAT medium and select for positive cells
Then harvest the monoclonal antibodies
what does -omab, -imab and -umab mean?
-omab = derived from mice
-imab = recombinant
-umab = human only
How are recombinant antibodies made?
library of V-segments and library of bacteriophages
What are the THERAPEUTIC uses of manufactured antibodies?
prophylactic against microbial infection e.g. IVIG, synagis
Removal of T cells from bone marrow grafts e.g. anti-CD3
Block cytokine activity e.g. anti-TNFa
What are the DIAGNOSTIC uses of manufactured antibodies?
blood group serology
immunodiagnosis: infectious disease, autoimmune, allergy, malignancy
What is the ELISA test?
Enzyme linked immuno-sorbent assay
Antibodies linked to an enzyme are added to a well that could contain the target antigen
If present, bind so cannot be washed away
Uncoloured substrate added, the enzyme on the antibody converts it to a coloured substrate
Light absorbance can be measured via mass spectrometer
What is rapid testing?
put on a sample
capillary action along the strip moves the sample alaong
antibodies conjugated to gold particle bind to antigen
Test line - visible if positive test
Control line - anti-G antibodies - visible line to show it's working
What is the problem with immune complexes?
result in inflammation and complement activation
How is immunodeficiency determined?
serum immunoglobulin levels - using ELISA, electrophoresis, nephelometry
Specific antibodies - using ELISA - protein antigens, polysaccharide antigens
Lymphocytes subsets (Flow cytometry) - CD3, CD4...
What does serum electrophoresis show?
Thick band of gamma globulin - active immune response
sharp thin band of gamma globulin - monoclonal expansion of B cells - myeloma