Development of an antigen heterologous enzyme linked immunosorbent assay for measurement of corticosterone in rat serum.

Homologous and heterologous combinations of enzyme conjugate and antibody in steroid enzyme immunoassay (EIA) influences unlabeled steroid recognition by antibody that affects sensitivity of the assay. To develop corticosterone enzyme linked immunosorbent assay (ELISA), antibodies were generated against corticosterone-3-carboxymethyloxime-bovine serum albumin (corticosterone-3-CMO-BSA) and corticosterone-21-hemisuccinate-bovine serum albumin (corticosterone-21-HS-BSA). Four horseradish peroxidase (HRP) enzyme conjugates were prepared using two corticosterone derivatives (corticosterone-3-CMO and corticosterone-21-HS) and two cortisol derivatives (Cortisol-3-CMO and Cortisol-21-HS). Eight combinations of homologous and heterologous assays were evaluated. The use of antigen heterologous combination resulted in development of assay. The developed assay is simple, direct, and convenient to use, as it permits the direct addition of the serum sample in to the assay, and it requires only 1.5 hours to complete.