25th Page Flashcards
Radioimmunoassay (RIA)?
Developed by Rosalyn Yalow and Solomon Berson for measurement of insulin in plasma.
3 radioactive substances as labels in Radioimmunoassay (RIA)
3H (Tritiated Hydrogen)
125I (label of choice).
131I
What are the advantages of Enzyme Immunoassays?
Cheap and readily available
long shelf-life
easily adapted to automation
sensitivity can be achieved without disposal problems
little reagent is necessary to produce high sensitivity
uses quali or quanti to determine actual conc. of analyte
Competitive RIST?
Measures Total IgE or Ag-specific IgE.
Radioactivity is indirectly proportional to the analyte concentration.
Noncompetitive RIST?
NON-direct
radioactivity is directly proportional to the analyte.
What are the 3 types of Heterogeneous Enzyme Immunoassays?
Competitive ELISA
Non-competitive ELISA
Sandwich (capture) ELISA.
What is EMIT?
Enzyme Multiplied Immunoassay Technique, based on the principle of change in enzyme activity as specific Ag-Ab combinations occur.
Enzyme activity is directly proportional to the concentration of antigen present.
Part of non-competitive assay
What are Fluorescent Immunoassays?
Uses fluorophores or fluorochromes as labels.
Examples:
FITC
TRITC
FITC (fluorescein isothiocyanate) emits what color
Green
TRITC (tetramethyl-rhodamine isothiocyanate) emits what color
RED
What are the two types of Fluorescent Immunoassays?
- Direct IF - detects unknown antigen (e.g., diagnosis of Primary Syphilis).
- Indirect IF - detects unknown antibody (e.g., diagnosis of autoimmune disease).
What is RAST?
Radioallergosorbent Test, where radioactivity is proportional to the concentration of specific binding antibodies.
IRMA
The count supernate is directly proportional to the px antigen
