Measurement of inhibin A: a modification to an enzyme-linked immunosorbentassay

Inhibin A is a useful prenatal marker of Down syndrome, Currently, the avai lable enzyme-linked immunosorbent assays (ELISAs) for inhibin A are based u pon the same paired monoclonal antibodies. In the present study we have con firmed for one of those ELISAs that short-term sample storage as whole bloo d leads to a significant decline in detectable inhibin A and that this is m ost likely due to erythrocyte catalase interference with a critical oxidati on step in the assay. While this interference can be eliminated by heating the samples pre-assay, this process is labour intensive. In the present stu dy we have demonstrated that the addition of 3-amino-1,2,4-triazole (AT), a catalase 'suicide' inhibitor, also prevents the decline of inhibin A level s in samples stored as whole blood. We suggest that the addition of AT to s amples prior to assay is a simple modification to the inhibin A ELISA that affords optimum performance. Copyright (C) 2001 John Wiley & Sons, Ltd.