Sandwich enzyme immunoassay of aprotinin.

Enzyme immunoassay, using the rabbit antiaprotinin Fab'-beta-D-galactosidase complex and the rabbit antiaprotinin IgG-coupled polystyrene ball as a solid phase was used to measure sera levels of aprotinin. The least measurable amount of the aprotinin in the enzyme immunoassay was bout 0.002-0.005 kallikrein inhibitor unit/ml. In the enzyme immunoassay of aprotinin in serum, the influence of serum on the assay was eliminated by using a buffer with gelatin as a sample diluent in the first step of the antigen and antibody reaction. Aprotinin level in the serum, as estimated by enzyme immunoassay correlated highly with levels obtained by inhibition assay.