Enzyme-linked Immunosorbent Assay (ELISA) was developed in 1970 and rapidly became accepted as a standard routine assay technology. The assay format is sometimes referred to as EIA (Enzyme Immuno Assay).
The assay format combine the specificity of antibodies with the sensitivity of simple enzyme assays, by using antibodies or antigens coupled to an easily-assayed enzyme. ELISAs can provide a useful measurement of antigen or antibody concentration. There are two main variations on this method: The ELISA can be used to detect the presence of antigens that are recognized by an antibody or it can be used to test for antibodies that recognize an antigen.
An ELISA is a five-step procedure:
There are many different types of ELISAs. Currently the most important ones are: