Intracellular cytokine accumulation in CD161⁺ NK cells from cultures of Lin⁻ cells with IL-2 to determine the proportion of cells capable of cytokine production, and cytokine production by distinct subsets.

Umbilical cord blood 10-day NK cells (top), and CD3⁻/CD161⁺ cells from 30-day primary cultures of Lin⁻ cells with IL-2 and Sl/Sl⁴hSCF²²⁰ feeder cells (bottom) were stimulated (6 hours, 37°C) with PMA and Ca⁺⁺ ionophore (see “Materials and methods”). Surface phenotype and expression of the indicated cytokines were detected simultaneously (3-color immunofluorescence) on gated CD161⁺ cells as described in “Materials and methods,” and analyzed as in Figure 2. Percent positive cells is indicated in each quadrant. Experiment representative of at least 4 performed with similar results with each Ab combination.