Enzyme Immunoassay (EIA) Terminology Immunology Review 391
TERM EXPLANATION
EIA Any immunoassay that uses an enzyme as label. A substrate is added to measure enzyme activity.
Direct EIA 1st type of EIA developed. Competitive. Enzyme-labeled reagent is part of initial ag-ab rxn. All reactants added at same
time. 1 incubation & 1 wash.
Indirect EIA Noncompetitive EIA. Enzyme-labeled reagent isn’t involved in initial ag-ab rxn. 2 incubations & 2 washes. More sensitive
than direct assays. Also known as enzyme-linked immunosorbent assay (ELISA). See next card for more details.
Solid phase Reagent ag or ab bound to support medium, e.g., polystyrene test tubes, microtiter plates, cellulose membranes, glass
beads.