Equivalent recognition of free and act-complexed PSA in a monoclonal-polyclonal sandwich assay is conferred by binding specificity of the monoclonal antibody
✍ Scribed by Zeqi Zhou; E. Glenn Armstrong; Alexander Belenky; James V. Freeman; Kwok K. Yeung
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 82 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0887-8013
No coin nor oath required. For personal study only.
✦ Synopsis
The Bayer Immuno 1 TM PSA Assay measures free and ACT-complexed PSA on an equimolar basis, although it uses a monoclonal antibody (MM1) for capture and polyclonal antibodies for detection. Competitive inhibition studies using antibodies directed at various epitopes on PSA and PSA-ACT demonstrated that the capture antibody, MM1, does not bind to free PSA simultaneously with antibodies against Epitope E which is exposed only in free PSA. Affinity studies showed that the affinity constants of MM1 for both free PSA and PSA-ACT are similar. One explanation for the properties of MM1 is that it precludes the binding of antibodies to Epitope E due to steric hindrance. Alternatively, the binding of MM1 causes a conformation change within the free PSA molecule, so that Epitope E is altered in a way that causes a loss of binding affinity. The unusual properties of MM1 are responsible for the equimolar response of this monoclonalpolyclonal sandwich assay for free and ACT-complexed PSA.