Received on April 20, 2007
Accepted on September 28, 2007

Endocrinology and Metabolism

Analytical Validation and Biological Evaluation of a High–Molecular-Weight Adiponectin ELISA

¹ Millipore Bioscience Division, Millipore Corporation, St. Charles, MO
² Division of Laboratory and Experimental Medicine, Eli-Lilly Company, Indianapolis, IN
³ Department of Nutrition, University of California, Davis, CA
⁴ Division of General Surgery, Oregon Health and Science University, Portland, OR
⁵ Touchstone Diabetes Center, The University of Texas Southwestern Medical Center, Dallas, TX

^* To whom correspondence should be addressed. E-mail: Madhur_Sinha{at}Millipore.com.

Background: Of the 3 circulating multimeric forms of adiponectin, the high–molecular-weight (HMW) form, as measured by size-exclusion and/or immunoblotting techniques, is a better index of insulin sensitivity for monitoring health and disease than is total adiponectin. We aimed to develop a simple ELISA to measure HMW adiponectin.

Methods: We pretreated serum or plasma samples with digestion solution containing proteinase K (Millipore, ESDS). HMW (Millipore, EZHMWA-64K) and total adiponectin (Millipore, EZHADP-61K) concentrations were measured in treated and untreated samples, respectively, from 108 individuals and from 20 morbidly obese patients before and at 1, 3, 6, and 12 months after gastric-bypass surgery.

Results: The ELISA has a dynamic range of 3–200 µg/L and a detection limit of 0.8 µg/L. Intraassay and interassay CVs were <4% and <10%, respectively. Sampledilution curves paralleled the calibration curves. Fast protein liquid chromatography profiles of the proteinase K-treated samples revealed predominantly HMW adiponectin. Values for HMW adiponectin produced with this method are comparable with those obtained with Western blot analysis (y = 0.77x- 0.15; r = 0.96; n = 56). Body mass index (BMI)- and sex-related changes were more pronounced for HMW adiponectin and percentage of HMW adiponectin than for total adiponectin. HMW and total adiponectin increased after bypass surgery, but changes in HMW adiponectin were more pronounced and preceded changes in total adiponectin.

Conclusion: This simple, rapid ELISA for HMW adiponectin recognizes the HMW isoform, produces results closely correlated with those obtained with Western blotting, and appears to better distinguish BMI-, sex-, and weight loss–associated differences than assays for total adiponectin.