immunoassay enzymatic method enzyme immunoassay 2020-05-26T17:34:31Z EIA Enzyme immunoassays (EIAs) use antibodies to detect the presence of antigens in solution in microtiter plates or in vivo. There are many different types of EIAs, but they all involve an antibody molecule whose constant region binds an enzyme, leaving the variable region free to bind its specific antigen. MMO:0000713 measurement_method_ontology slaulede