Topic overview

Start with the big picture

ELISA combines a solid phase, a capture antibody or antigen, an enzyme-labeled detector, and a substrate to generate a measurable signal. The format shapes how the target is detected: sandwich assays bind the antigen between capture and detection antibodies, while competitive assays produce an inverse relationship between analyte amount and signal. Blocking and washing help limit nonspecific background, and results can be quantified against a standard curve. Laboratory interpretation also considers performance measures such as sensitivity, specificity, detection limit, and variation. ELISA offers practical advantages, but matrix interference, cross-reactivity, and the hook effect can affect results. The broader lesson places ELISA alongside chemiluminescent, radioimmunoassay, and lateral-flow methods, with attention to quality control and applications.