The 2E6⁺cells from spleen produce large amount of IFN-α upon influenza virus (strain PR8) stimulation. Spleen cells were stained with biotinylated 2E6 mAb followed by avidin-conjugated magnet beads. The 2E6⁺ and 2E6^– cells were separated using Auto MACS. Each group (2E6⁺, 2E6^–, whole spleen cells) was plated onto 96-well round-bottom plates (5 × 10⁴ cells/well). Experiments were performed in triplicate. Then, either medium alone or influenza virus PR8 were added to the wells to a total volume of 200 μL and incubated at 37°C for 24 hours. IFN-α in supernatants was measured by ELISA. Values represent mean ± SD from triplicate samples.