1. CLS 1113 Introduction to Clinical Laboratory Practices
Unit 5
Labeled Immunoassays
Chapter 10

2. 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

3. Elements of Labeled Immunoassays
Ligands
Antibodies
Standards or Calibrators
Separation Methods
Detection of Label

4. Radioimmunoassay (RIA)
Competitive binding assay
Uses a radioactive substance as a label
3H - Tritiated hydrogen
125I - Iodine 125

5. Radioimmunoassay
Two Types
Number 1

6. Radioimmunoassay
Number 2

7. Enzyme Immunoassay Immunoassay labels Enzymes Cheap Readily available
Long shelf life
Easily adapted to automation

8. ELISA, Figure 10-4, page 149

9. 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.

10. ELISA: Sandwich method
Figure 10-5, page 149

11. 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.

12. Fluorescent Immunoassay:
Direct and Indirect

13. 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.