Analysis of intracellular accumulation of IL-5 and IL-13 in CD161⁺ and CD56⁺ NK cells during differentiation to determine the stage(s) at which IL-13 is produced and whether the same or distinct NK cell subsets produce the 2 cytokines.

Cells from primary cultures of CD34⁺ cells with Flt3-L and IL-2 were stimulated as in Figure 3. Intracellular cytokines and surface phenotype were analyzed simultaneously in 4-color immunofluorescence with ECD–anti-CD3, biotin-labeled anti-CD56 alone (bottom) or combined with anti-CD161 (top) detected with streptavidin-CyC, FITC–anti–IFN-γ, and PE–anti–IL-5 or PE–IL-13 mAbs, as indicated. Analysis was performed, as indicated, on gated CD3⁻/CD56⁺ or CD3⁻/(CD161/CD56)⁺ cells (referred to as CD161⁺ NK cells in the text). Percent positive cells is indicated in each quadrant. Percentages in the left-hand plots are percent gated cells in the total population. Experiment representative of 3 performed with similar results.