DEVELOPMENT OF RADIOIMMUNOASSAY FOR HUMAN LEPTIN

Using recombinant human leptin, we have produced an antiserum for huma n leptin and developed a radioimmunoassay (RIA) specific and sensitive for human leptin. We detected leptin-like immunoreactivity (-LI) in c ulture media of adipose tissue from subcutaneous abdominal fat in huma n. The plasma human leptin-LI concentration in nonobese subjects (17.6 < body mass index (BMI) < 23.0) was 5.6 +/- 1.3 (mean +/- SE) ng/ml, while that in obese subjects (29.0 < BMI) was 43.0 +/- 43.0 +/- 9.4 (m ean +/- SE) ng/ml. In gel permeation chromatographic analyses, leptin- LI in culture media and plasma consisted of single component emerging at the elution position of recombinant human leptin. These findings in dicate that leptin is secreted from the adipose tissue into the circul ating blood as a large molecular form corresponding to recombinant lep tin. The RIA developed in the present study will be a powerful tool to investigate the physiological and pathophysiological significance of leptin in human. (C) l996 Academic Press, Inc.