摘要 |
<p>A one-step assay for the free portion of a ligand in a biological sample involves incubating a mixture of the sample with a labelled antibody for the ligand and a ligand analogue which competes with the ligand for binding to the antibody. The assay is characterized by using a monoclonal antibody and by choosing a ligand analogue which has a lower affinity for the antibody that does the ligand. An insolubilised ligand analogue preferably has a binding affinity for the antibody from 0.01% to 10% of that of the ligand. Ligand/ligand analogue pairs exemplified are T4/T3 (Thyroxine/Triiodothyronine); Testosterone/etiocholanol; and T3/T2.</p> |