Interference by 2, 3-dimercapto-1-propanol (BAL) in angiotensin I radioimmunoassay

The angiotensinase inhibitor 2,3-dimercaptopropanol (BAL) interferes with peptide-antibody binding when certain sensitive antisera are used in angiotensin I radioimmunoassay systems. Three of nine antisera tested showed sufficient interference to produce serious errors in data obtained using these antisera together with BAL. For PRA determinations in human plasma, at both pH 5.7 and pH 7.3, relationships between different PRA'S are altered, and results of renin stimulation tests are changed in unpredictable ways. Determination of renin concentration in rat plasma does not require use of BAL as inhibitor, and it is best avoided. For human plasma renin determinations, use of BAL-sensitive antisera should be avoided, since there is no satisfactory way to correct data for the resulting error. BAL itself, rather than its oxidation products, is probably the interfering substance. The interference appears to be due to an interaction between BAL and the BAL-sensitive antiserum. It is not related to the known actions of BAL as chelating or reducing agent.