PIP1PICATION PORE IgG CONTROL OF SPECIFICITY 111CR PURITY PEROXIDASE I AT ACTIVATION COUPLiNG PEPSIN DIGESTION GEL FILTRATION ON SEPHACRYL S 200 F(b’)2 FRAGMENTS LPEROXIDASE ANTIBODY CONJiJ

Enzyme immunoassaysare very useful for the detectionof low concentrationsof coagulationproteinsand pathological markers in plasma. Analytes in the ng/mL range are measurable with good reproducibility with intraand interassay CVs of less than 5% to 10%. “Sandwich” methods have been developed for von Willebrand factor (plasma concentration about 8 .&.g/mL,Factor IX (5 p.g/mL),proteinC (4 g/mL), and Factor X (10 g/mL). However, this technique is only suitable for macromolecules; for low-molecular-mass peptides such as fibrinopeptide A a competitive method is used. Normal concentrations offibrinopeptide A arebelow 3 ng/mL, with greater values suggesting in vivo generation of thrombin; thus this test is quite useful in detecting thrombosis. Reagents for both the sandwich and competitive methods are commerciallyavailable and cost effective, and have a longershelf-lifethan those for radioimmunoassays.