Comparison of Labeled Immunoassays Immunology Review 395
Labels
Detection
Type(s) of assays
available
Advantages
CHEMILUMINESCENT
IMMUNOASSAY (CIA)
Luminol, acridium esters,
ruthenium derivatives,
nitrophenyl oxalates.
Chemiluminescent mole-
cules produce light from
chemical rxn.
Competitive & noncompet-
itive. Heterogeneous &
homogeneous.
Same as EIA. Automated.
FIA
Fluorescein, rhodamine.
Fluorochromes absorb
energy from light source,
convert to longer wave-
length (lower energy).
Usually competitive.
Heterogeneous &
homogeneous.
Same as EIA. Automated.
RIA
(^125) I, (^131) I, (^3) H.
Radioisotopes
emit radioactivity.
Competitive/
heterogeneous.
Sensitivity.
Specificity.
EIA
Alkaline phosphatase,
horseradish peroxidise,
- D-galactosidase,
glucose-6-phosphate
dehydrogenase.
Enzymes react with
substrate to produce
color change.
Mostly noncompetitive
now. Heterogeneous &
homogeneous.
Sensitivity. Specificity. No
health hazard or disposal
problems. Reagents with
long shelf life. Can be
automated.
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