Milk-specific antibody measurement by ELISA: development of an assay

This paper describes the development of a simple, sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the measurement of serum IgG, IgA and IgM anti-bodies to cow's milk protein. The specificity of this assay was determined by preparing immunosorbents of cow's milk and human serum albumin (HSA). Fractionation of the antiserum-enzyme label by gel filtration and affinity chromatography showed that the conjugate preparation contained moieties of antiserum-enzyme, and antiserum-enzyme polymers. The preparation also contained enzyme-enzyme and antiserum-antiserum conjugates. Purification of the labelled reagent did not improve the sensitivity. The reagents and conditions used have been analyzed for purposes of standardisation.