Direct, simplified, and sensitive assay of angiotensin II in plasma extracts performed with a high-affinity monoclonal antibody
Simon, D.; Romestand, B.; Huang, H.; Badouaille, G.; Fehrentz, J.A.; Pau, B.; Marchand, J.; Corvol, P.
Clinical Chemistry 38(10): 1963-1967
1992
ISSN/ISBN: 0009-9147 PMID: 1394979 Document Number: 400209
A very simple, fast, and sensitive RIA of angiotensin (Ang) II has been developed, based on a monoclonal antibody with high affinity and specificity, making possible the direct measurement of circulating Ang II in human plasma after solid-phase extraction. The purified monoclonal antibody 4D8 has an association constant of 1.3 times 10-11 L/mol with Ang II and a cross-reactivity of lt 1% for Ang I. The assay can detect as little as 0.8 fmol of Ang II in 2 mL of plasma and is not influenced by the presence of Ang I. Analytical recoveries between 112% and 116% were obtained for Ang II added to human plasma at physiological concentrations. Comparison of the RIA with a reversed-phase, high-performance liquid chromatographic method followed by RIA to measure Ang II in human plasma samples from normal and hypertensive subjects-and from normotensive subjects before and after an acute inhibition of angiotensin-converting enzyme with captopril (50 mg)-showed a high degree of correlation (r-2 = 0.93) between the two methods.