AN IMMUNOLOGICAL METHOD FOR THE DETECTION OF CAPTOPRIL-PROTEIN CONJUGATE

To clarify the mechanism of cytotoxicity induced by captopril (Cp), in teractions between tissue protein and Cp were studied by the enzyme-li nked immunosorbent assay (ELISA) method. The amide-linked adducts [hem ocyanin from keyhole limpet-Cp adduct (KLH-Cp) and poly-L-Lys-Cp adduc t (pLys-Cp)] using carbodiimide, and a disulfide-linked adduct [ovalbu min-Cp adduct (OVA-Cp)] were prepared. To determine the formation of t he protein-Cp adduct, rabbit antisera against KLH-Cp was employed. The immunoreactivities with pLys-Cp and OVA-Cp against anti KLH-Cp sera w ere elevated when compared with the unmodified protein. With the inhib ition ELISA, this antisera was useful for detecting the Cp disulfide-l inked conjugate. In kidney cytosol, a high level of immunoreactivity w as observed. Plasma and liver cytosol reactivities were similar, and s imilar to 40% against kidney cytosol. Thus, a method for the detection of the Cp-protein adduct using ELISA has been established. Formation of the Cp-protein adduct was observed in rat plasma and in liver and k idney cytosol. These findings suggest the possibility that the formati on of Cp-protein adduct is partially related to cytotoxicity in liver.