Measured by its binding ability in a functional ELISA. When Recombinant Cynomolgus Monkey ICOS Fc Chimera is immobilized at 0.5 μg/mL (100 μL/well), the concentration of Recombinant Cynomolgus Monkey B7-H2 Fc Chimera that produces 50% of the optimal binding response is 4-20 ng/mL.