REPRODUCIBILITY OF ERYTHROCYTE POLYAMINE MEASUREMENTS AND CORRELATIONWITH PLASMA MICRONUTRIENTS IN AN ANTIOXIDANT VITAMIN INTERVENTION STUDY

Erythrocyte polyamine measurements have been previously investigated a s candidate biomarkers for hyperproliferation and recently as a potent ial intermediate endpoint in clinical chemoprevention trials with difl uoro-methylornithine, an inhibitor of polyamine biosynthesis. This stu dy was performed to determine the reproducibility of erythrocyte polya mine measurements and their possible correlation with plasma micronutr ients in seven healthy adults in an antioxidant vitam in intervention study. As part of this cross-over intervention study, three subjects t ook beta-carotene (31.4 mg/day) plus D-alpha-tocopherol acetate (720 I U/day) supplements during the first 3 months and four subjects took th e supplements during the second 3 months. Heparinized blood samples we re collected at baseline and every month over total 6 months for simul taneous determination of erythrocyte polyamines and plasma micronutrie nts by the high-performance liquid chromatographic method. For all the measures of erythrocyte polyamines the intraindividual variation was smaller than that between subjects, and three or four measurements req uired to accurately characterize long-term erythrocyte polyamines for an individual. The intra-class correlations were moderately high for a ll erythrocyte polyamine measurements, indicating a good reproducibili ty for intra-individual erythrocyte polyamine measurements. Based on m onthly values, significant inverse correlations were found between ery throcyte spermidine and the plasma levels of retinol (r = -0.50) and l utein (r = -0.52). There were also significant inverse associations be tween erythrocyte spermine and plasma levels of alpha-tocopherol (r = -0.29), lutein (r = -0.44), lycopene (r = -0.29), beta-cryptoxanthin ( r = -0.30), and total carotenoids (r = -0.29). The effects of suppleme ntation upon the associations between erythrocyte polyamines and plasm a nutrient levels were additionally addressed. The results indicate an I acceptable longitudinal reproducibility of erythrocyte polyamine me asurements, support the hypothesis that erythrocyte polyamine measurem ents may be correlated with plasma levels of certain nutrients, and su ggest a further biomarker application in cancer prevention trials invo lving dietary modifications or specific relevant micronutrients. (C) 1 996 Wiley-Liss, Inc.