Description: The Human Cytokine Positive Control Cells are recommended for use as positive control cells when establishing an intracellular cytokine staining protocol. Normal human peripheral blood cells were stimulated for two days with immobilized anti-human CD3 (10 µg/mL), soluble anti-human CD28 (2 µg/mL), and recombinant IL-2 (10 ng/mL) and IL-4 (20 ng/mL), followed by three additional days of culture with IL-2 and IL-4. The cells were then restimulated with PMA (5 ng/ml) and ionomycin (500 ng/ml) in the presence of Brefeldin A for 4 hours. These cells contain subpopulations that express IL-2, IL-4, IL-13, IFNγ, and GM-CSF. The cells have been fixed with formaldehyde and are in a stabilizing buffer so that they may be stored at -80°C for up to six months or at 2-8°C for up to one month.