Calibration curve for PAPP-A sandwich immunoassay. Capture: PAPP A antibody [4G11] (GTX10192) biotinylated; Detection: PAPP A antibody [10H9] (GTX10195) labeled with stable Eu3+ -chelate; Antigen: htPAPP-A; Mixture of antibodies and antigen was incubated for 30 minutes at room temperature in streptavidin-coated plates.