Effects of a leptin stimulation on NK-cell-tumor-cell-conjugates and IFN-γ and Granzyme production of human NK cells. PBMCs from healthy normal weight and obese subjects were stimulated with 50 nM human recombinant leptin or treated with vehicle for 24 h. Thereafter, cells were stained with antibodies and analyzed by flow cytometry. (A) Numbers of NK-cell-tumor-cell-conjugates (K562 erythroleukemia line), (B) Granzyme positive NK, (C) IFN-γ positive NK cells are shown as percentage of NK cells. Data are expressed as mean + SEM. Significant effects of leptin stimulated IFN-γ positive vs. non-stimulated NK cells in the normal weight group are indicated by an asterisk *p < 0.05.