Antibodies as diagnostic tools Flashcards Preview

Y2 LCRS - Diganostics 3-5 > Antibodies as diagnostic tools > Flashcards

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

Fusion protein


What are the THERAPEUTIC uses of manufactured antibodies?

prophylactic against microbial infection e.g. IVIG, synagis

Anti-cancer therapy

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


What is flow cytometry?

Specific marker (CD) used against various lymphocytes

CD3+ for T cells

CD56+ for NK cells

monoclonal antibody fluorescently labelled

pass through laser beam in a stream and fluorescence is detected - each cell can then be characterised based on fluorescence