Assessment of urinary F(2)-isoprostanes in experimental and clinical studies: mass spectrometry versus ELISA.

Assessment of Urinary F2-Isoprostanes in Experimental and Clinical Studies: Mass Spectrometry Versus ELISA To the Editor: Ojeda and colleagues reported that oxidative stress renal markers contribute to sex differences in blood pressure in adult growth-restricted offspring rats. The antibody used in the ELISA kit used by Ojeda et al isspecificfor15(S)-8-iso–PGF2 , 2 (http://www.oxfordbiomed.com/sites/ default/files/spec_sheet/EA85.120426.pdf) one of 64 possible F2-isoprostanes. At first glance, ELISA and gas chromatography-mass spectrometry (GC-MS) seem to correlate (Figure, A); however, the Bland-Altman method reveals enormous differences and systematic errors in the ELISA method (Figure, B). Lack of analytically satisfactory agreement applies to another commercially available 15(S)-8-iso– PGF2 ELISA kit (http://www.caymanchem.com/pdfs/516351.pdf). 15(S)-8-iso–PGF2 is excreted in the urine in free and conjugated forms (Figure C). The lack of appreciable biological variation in urinary excretion in humans and rats (58 16 pg/mg creatinine; 1 female, 4 male) and the manifold higher reported 15(S)-8-iso-PGF2 levels reveal serious analytic shortcomings with the use of 15(S)-8-iso– PGF2 ELISA kits. This may compromise the scientific outcome. Inclusion of clean-up procedures is likely to improve the analytic performance of ELISA kits. Yet, reliable assessment of 15(S)-8-iso– PGF2 in experimental and clinical study samples is best accomplished by tandem mass spectrometry-based methods. Disclosures None.