Whole-blood culture
Whole blood cells (500 µL of blood) were incubated with 20 μg/ml concanavalin A (Con A, Sigma-Aldrich, St. Louis, MO, USA) at 37°C under 5% CO2 for 24 hours using 48-well plates (Corning Inc., Corning, NY, USA). Collected culture supernatants were assayed for IFN-γ by Bovine IFN-γ ELISA Development Kit (Mabtech, Nacka Strand, Sweden) according to the manufacturer’s instructions.