Synergistic activation of Ca2+ flux in resting NK cells by co-crosslinking pair-wise combinations of receptors. (A-B) NK cells were preincubated with mAbs to indicated receptors on ice, loaded with Fluo-4 and Fura Red, resuspended in HBSS 1% FBS, and prewarmed at 37°C. Cells were analyzed by flow cytometry. After 30 seconds, secondary F(ab′)2 goat anti-mouse IgG was added to each sample. (A) FL-1/FL-3 ratios are plotted as a function of time. Black lines show activation with isotype control. Blue lines show activation by the single receptors, indicated in blue. Green lines show activation by the single receptors, indicated in green. Red lines show activation by the combination of both receptors. (B) The peak FL-1/FL-3 ratio after cross-linking of indicated receptor combinations was measured in several independent experiments. Bars indicate the SD (≥ 3 independent experiments).
