Expression of IL-2Rα, IL-2Rβ, and IL-2Rγ by B lymphocytes. PBMC from blood collected on heparin were treated by MoAbs 33B3, CF1, and 3B5. Characterization of the population was achieved by treatment with anti-CD19 and anti-CD23 MoAbs. FITC-labeled Fab fragment anti-IgG was used, followed by PE-conjugated anti-CD4 + FL3-conjugated anti-CD14 MoAbs. CD14⁺ monocytes were excluded for easier analysis. Quadrant setting distinguishing positive immunofluorescence from background fluorescence was determined by staining with isotype-matched control MoAbs. The percentage of positive cells for the different markers is indicated.