title: A simple theoretical treatment of a competitive enzyme-linked immunosorbent assay (ELISA) and its application to the detection of human blood group antigens.
abstract: A theory has been developed to explain the behaviour of a competitive enzyme-linked immunosorbent assay (ELISA) in which an immobilized antigen competes with a liquid-phase antigen for a limiting amount of antibody. The binding of antibody to antigen on a solid surface (microtitre well) is described in terms of Langmuirian adsorption with a binding constant kappa. Two equations are presented to describe the behaviour of the ELISA signal as a function of competing antigen concentration; an exact equation and an approximate equation which can be used when the surface coverage of the immobilized antigen is not known. It is shown how curves of ELISA signal vs. competing antigen concentration depend on K/kappa [antibody]. The theory has been tested using several immobilized blood group A antigens competing with ovarian cyst fluid A substance and found to adequately describe these competitive ELISAs which have a detection limit of approximately 1 ng of blood group antigen.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Biological Sciences, University of Manchester, U.K.
authors.forename: V
authors.initials: V
authors.lastname: Chapman
authors.forename: S M
authors.initials: SM
authors.lastname: Fletcher
authors.forename: M N
authors.initials: MN
authors.lastname: Jones
mesh_terms: D001667:Binding, Competitive; D001789:Blood Group Antigens; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007700:Kinetics; D010048:Ovarian Cysts / Q000032:analysis; D012044:Regression Analysis
chemical_list: D001789:Blood Group Antigens