Enzyme/anti-enzyme monoclonal antibody soluble immune complexes (EMAC): their use in quantitative immunoenzymatic assays.

Enzyme/anti-enzyme antibody soluble immune complexes were prepared with monoclonal mouse antibodies (MA) which were directed against peroxidase (PO) and beta-galactosidase (GAL). These enzyme monoclonal antibody complexes (EMAC) functioned as markers to quantify mouse antibodies using an enzyme immunoassay which incorporated an anti-mouse Ig as the bridge between the EMAC and the specific antibody bound to an antigen immobilized on a polystyrene plate. EMAC prepared with PO (PO-MAC) or with GAL (GAL-MAC) were both effective in quantifying polyclonal as well as monoclonal mouse antibodies, and gave sensitivity equal or superior to that obtained with covalent enzyme/anti-mouse Ig conjugates. The smaller amount of antibodies detected with EMAC depended on the affinity of both the antibody tested and the monoclonal antibody used to prepare EMAC. This method is an improvement on the 'antibody bridge' method, because EMAC can be prepared easily by simply mixing the enzyme and the MA at the appropriate amounts 2 h prior to use. In addition, EMAC can be prepared using crude preparations of enzyme and unpurified ascitic fluids containing the MA, thus decreasing the cost of the test considerably.