CLS 1113 Introduction to Clinical Laboratory Practices

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CLS 1113Introduction to Clinical Laboratory
Practices

• Unit 5
• Labeled Immunoassays
• Chapter 10

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Labeled Immunoassays

• Designed for Ags and Abs that DO NOT react in
  precipitation or agglutination tests due to their
  small size or low concentrations.
• Indirect method of detection
• Competitive vs. Non-Competitive
• Test Antigen or Antibody competes for binding
  sites

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Elements of Labeled Immunoassays

• Ligands
• Antibodies
• Standards or Calibrators
• Separation Methods
• Detection of Label

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Radioimmunoassay (RIA)

• Competitive binding assay
• Uses a radioactive substance as a label
• 3H - Tritiated hydrogen
• 125I - Iodine 125

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Radioimmunoassay

• Two Types
• Number 1

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Radioimmunoassay
Number 2
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Enzyme Immunoassay

• Immunoassay labels
• Enzymes
• Cheap
• Readily available
• Long shelf life
• Easily adapted to automation

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ELISA, Figure 10-4, page 149
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Enzyme Immunoassay

• Enzymes are naturally occurring molecules that
  catalyze specific biochemical reactions.
• They react with suitable substances to produce
  products that are chromogenic (color),
  fluorogenic, or luminescent.

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ELISA Sandwich method Figure 10-5, page 149
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Fluorescent Immunoassay

• Similar to ELISA but a fluorochrome is used
  rather than an enzyme.
• Fluorochromes have the ability to absorb energy
  from light an emit it at a longer wavelength.

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Fluorescent Immunoassay Direct and Indirect
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Chemiluminescent Immunoassays

• Chemiluminescence is the production of light
  energy due to a chemical reaction.
• Certain substances when oxidized can give off
  short or long bursts of light energy.