SERUM LEPTIN LEVEL - POSSIBLE ASSOCIATION WITH HEMATOPOIESIS IN ADOLESCENTS, INDEPENDENT OF BODY-MASS INDEX AND SERUM-INSULIN

1. The obese gene product leptin, secreted exclusively from adipocytes , was discovered to serve as a satiety factor and to play an important role in regulating body weight. In adults, the serum leptin level rep ortedly increases with the degree of obesity, Leptin receptors are exp ressed in various tissues, and recent in vitro studies suggest a role for leptin in haematopoiesis, 2. The present study was designed to cla rify the relationship between serum leptin and body mass index, periph eral blood cell counts, serum cholesterol, high-density lipoprotein-ch olesterol, insulin and cortisol levels in 299 Japanese male adolescent s aged 15-16 years. 3. With simple linear correlation, log [serum lept in] showed a strong correlation with body mass index (r = 0.56), log [ insulin] (r = 0.36) and leucocyte count (r = 0.22) (P < 0.001 for all) . There were also correlations with systolic blood pressure, erythrocy te count, haematocrit and high-density lipoprotein-cholesterol (P < 0. 01 for all). Even after adjustment for body mass index and log [insuli n], log [leptin] correlated with leucocyte (P = 0.004) and erythrocyte (P = 0.057) counts. Stepwise multiple regression analyses revealed lo g [leptin] to correlate significantly with body mass index, log [insul in] and the leucocyte count (P < 0.005 for all, r(2) = 0.399), 4. To o ur knowledge, this is the first clinical study to show the possible as sociation of serum leptin level with blood cell counts, independent of body mass index and serum insulin. We conclude that these data furthe r support a role for leptin in haematopoiesis.