The Nichols Advantage ACTH assay (Nichols Institute Diagnostics) uses one acridinium ester-labeled mouse monoclonal antibody that specifically binds to the C-terminal region of ACTH and one biotin-labeled goat polyclonal antibody that binds to the N-terminal region.
In the DPC IMMULITE ACTH assay (Diagnostic Products Corporation), a polystyrene bead within a test unit serves as the solid phase; the bead is coated with a monoclonal murine anti-ACTH antibody.
Two automated, nonisotopic ACTH assays have become available in recent years.
Nevertheless, discrepancies of results must be expected in a relevant number of tests when these different ACTH assays are used, possibly because of heterophilic antibodies.