Quantitation of circulating angiotensin II using commercial immunoassays

The quantitation of circulating angiotensin (ANG) II is not consistent among various commercially available kits. We measured plasma concentrations with three radioimmunoassay kits (Bühlmann Laboratories, Basel, Switzerland; Immuno Technology Service Production, The Netherlands, and Amersham, UK). The antibody specificity and their cross-reactions with ANG I decapeptide and with fragments of ANG II, were evaluated. The antibodies of the three kits cross-reacted with nearly all immunoreactive fragments of ANG II with intact carboxyl end. Cross-reaction with ANG I was detected with the antibody of the Immuno Technology Service kit only.