Enzyme-linked immunosorbent assay (ELISA)

There are many experimental designs possible for the enzyme-linked immunosorbent assay (ELISA). Depicted in this figure is a common antigen-binding assay using two antibodies. Anywhere from one to three antibody reagents may be used, and plates may also be coated with antibodies to interact with other molecules in solution. The reaction is measured by determining the absorption due to the chromophore generated by the enzyme linked to the detecting antibody. The solid-phase radioimmunosorbent assay is identical to that depicted here, except the detecting antibody is labeled with a radioactive isotope.