ELISA testing

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What does the acronym ELISA stand for?
  • Enzyme Linked ImmunoSorbent Assay
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What type of ELISA requires all the reagents to be added at once?
  • Homogenous
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What are the five basic steps of an ELISA test?
  • Adsorption of antigen/antibody onto solid phase
  • Addition of chosen sample and reagents
  • Incubation and washing
  • Addition of enzyme-labelled antigen/antibody
  • Addition of specific substrate
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Immunofluorescence

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The adsorption of light by a molecule is known as what?
  • Excitation
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What are the fluorescent dyes commonly known as?
  • Fluorochromes
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What are the advantages of indirect staining?
  • Brighter fluorescence
  • One preparation can be used to test many serum samples
  • Relative expressions of different antigens in the same cell can be tested
  • Loss of antibody during conjugation is limited
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What technique is used to provide a quantitative measure of immunofluorescence?
  • Flow cytometry
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Radioimmunoassay

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What are radioimmunoassays commonly used to detect?
  • Hormone levels in blood and tissue fluids
  • Serum proteins
  • Drugs
  • Vitamins
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What is the most common isotope used for radioimmunoassay?
  • Iodine-125
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Why is it important to measure the amount of antibody that binds to 50% of the labelled antigen?
  • Ensures the number of epitopes present exceeds number of antibody-binding sites
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What are the disadvantages of the radioimmunoassay?
  • Substances used are radioactive
  • Gamma radiation requires special counting equipment
  • Iodine naturally accumulates in the thyroid gland
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Agglutination

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What are the antibodies that produce agglutination known as?
  • Agglutinins
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What constitutes the end of the agglutination test?
  • The last tube showing distinct agglutination
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What does the titre represent?
  • The number of antibodies per unit volume of serum
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What is the prozone effect?
  • An inhibition of agglutination caused by an excess of antibodies
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What agglutination test is often used to test for rhesus disease?
  • Coombs test
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