Leptin receptor (Ob-R) expression and signaling pathway in PBMCs. PBMCs from healthy normal weight and obese subjects were stained with antibodies and analyzed by flow cytometry; (A) Numbers of Ob-R positive NK cells are shown in percentage of NK cells. Data are expressed as mean + SEM. Representative flow cytometry dot plots of ObR+ and ObR- NK cells from a normal weight (middle panel) and an obese individual (right panel) are shown. (B) Isolated PBMCs from normal weight and obese individuals (shown with body mass index (BMI)) were stimulated for 5 and 15 min with 50 nM human recombinant leptin. Phosphorylation of JAK2 (p-JAK2) was determined by Western blotting. Actin was used as control for equal loading. The experiment was repeated with 3 normal weight and 3 obese individuals, and a representative Western blot is shown. Quantitative analysis of the Western blots for p-JAK2. Values were normalized to actin and are shown as fold induction in arbitrary units (AU). Data are expressed as mean + SEM. Significant effects of obese vs. normal weight subjects are indicated by an asterisk *p < 0.05.