Optimization of assay conditions in monoclonal-based immunoradiometric assay

The production of relatively large amounts of pure monoclonal antibodies (MAb) has facilitated the development of MAb-based immunometric assays for a variety of clinically important analytes. 'Two-site' heterogeneous assays are now available which incorporate a labelled MAb and a second, different MAb coupled to a solid support. These assays possess certain advantages over the corresponding immunoassays including speed, precision, working range and specificity. They are largely dependent on two specific molecular interactions (labelled MAb-antigen; antigen--solid support MAb) and thus one might expect them to be particularly sensitive to assay conditions. With reference to two MAb--based two-site immunoradiometric assays (for human growth hormone and prolactin) which are being developed in this laboratory we wish to report the effect of various conditions including pH, ionic strength, buffer species etc. on assay response in order to emphasize the need for careful optimisation of monoclonal antibody based assays.