ELISA (Enzyme-Linked Immunosorbent Assay)

Solid-phase enzyme immunoassay quantifying antigens, cytokines, peptides, or antibodies in biological fluids.

Specifications & Metrics

type: Immunoassay
readout: Colorimetric, chemiluminescent, or fluorometric product generated by an antibody-conjugated enzyme
measures: Absolute concentration (pg/mL to μg/mL) of soluble proteins, hormones, antibodies, and drug biologics
format: Polystyrene 96- or 384-well microtiter plates (direct, indirect, sandwich, or competitive formats)
pioneer: Eva Engvall and Peter Perlmann (Stockholm University, published 1971)

First described by Eva Engvall and Peter Perlmann in 1971, ELISA replaced radioimmunoassays with non-radioactive enzyme-conjugated detection antibodies immobilized on solid-phase microtiter plates.
In a sandwich ELISA, a capture antibody coated on the plate well binds the target antigen from serum or supernatant, and a second enzyme-linked antibody (typically horseradish peroxidase or alkaline phosphatase) converts a substrate into a measurable color signal.
Competitive ELISAs measure small-molecule hormones (such as cortisol) and hapten drugs that have only one epitope by quantifying how sample analyte competes with enzyme-labeled analyte for limited antibody binding sites.