ABSTRACT
The term ELISA (enzyme-linked immunosorbent assay) was introduced by Engvall and Perlmann (1971) to describe a subset of the widely used immunoassay technique. ELISAs are distinguished from other immunoassays such as RIA by the use of an enzyme label linked either to the antigen or the antibody. This label in conjunction with a suitable substrate produces the assay signal. ELISAs are distinguished from other enzyme immunoassay (EIA) methods by the fact that one of the reagents is bound to a solid phase. In practice this solid phase usually takes the form of a 96-well microtitre plate. This gives the ability to handle many samples at one time and it facilitates automation of the assay. For a full discussion on all aspects of EIA the reader is referred to a number of books on the subject (Tijssen, 1985; Kemeny and Challacombe, 1988; Kemeny, 1991).
