The Binding Activity of Human CD81 with Anti-CD81 recombinant antibody. Activity: Measured by its binding ability in a functional ELISA. Immobilized Human CD81(CSB-MP004960HUd7) at 2 μg/mL can bind Anti-CD81 recombinant antibody. the EC<sub>50</sub> is 4.166-5.578 ng/mL.