Characterization of the optimized AP-FXIII ELISA. (A) General sensitivity. Titration of synthetic AP-FXIII in dilution buffer at 0.5, 0.25, 0.125, 0.0625, and 0.03125 ng/mL (0.12 nM-7.8 pM). Mean values from quintuplicates with error bars representing SD are shown. (B) Evaluation of the sensitivity toward AP-FXIII-Val34Leu polymorphism. Synthetic AP-FXIII-Val (●) and AP-FXIII-Leu (○) were titrated at 2.0, 1.0, 0.5, 0.25, 0.125, 0.0625, and 0.03125 ng/mL (0.5 nM-7.8 pM). Mean values from triplicates with error bars representing SD are depicted. (C) Competition analysis for mAb-1286 and mAb-6B11. AP-FXIII was detected either by mAb-1286 only (■), or in a mixture with mAb-6B11 at 1 μg/mL (), 2 μg/mL (), or 4 μg/mL (□). Mean values of triplicates with error bars representing SD are depicted.