Expression of IL-2Rα, IL-2Rβ, and IL-2Rγ by NK cells. (A) PBMC from blood collected on heparin were treated by MoAbs 33B3, CF1, and 3B5. Further characterization of the population was achieved by treatment with anti-CD8 and anti-CD16 MoAbs. FITC-labeled Fab fragment anti-IgG was used, followed by PE-conjugated anti-CD56 MoAb + FL3-conjugated anti-CD14 MoAbs. CD14⁺ cells were excluded for easier analysis. Quadrant setting distinguishing positive immunofluorescence from background fluorescence was determined by staining with isotype-matched control MoAbs. Vertical dotted line separates CD56 low from CD56 high cells. The percentage of positive cells for the different markers is indicated. (B) NK cells were highly purified from PBMC as previously described.47 The resulting CD56 population was treated by MoAbs 33B3, CF1, and 3B5 followed by FITC-labeled Fab fragment anti-IgG. The percentage of positive cells for the different markers is indicated.