ELISA

Abbreviation for enzyme-linked immunosorbent assay. An immunoassay, i.e. an antibody -based technique for the diagnosis of the presence and quantity of specific molecules in a mixed sample. It combines the specificity of an immunoglobulin with the detectability of an enzyme-generated coloured product. In one form, the primary antibody (specific to the test protein ) is adsorbed onto a solid substrate, and a known amount of the sample is added; all the antigen in the sample is bound by the antibody. A second antibody (conjugated with an enzyme) specific for a second site on the test protein is added; and the enzyme generates a colour change in the presence of a substrate reagent.