At the July 17–21, 2021 meeting of the International Society on Thrombosis and Haemostasis, the Precision BioLogic Inc. and the Affinity Biologicals, Inc. research team presented a poster that demonstrates how inactivated factor VIII reagent preparations that are employed for factor VIII activity assays and inhibitor assays may contain factor VIII that is detectable by immunoassay, albeit physiologically inactive.
Some lab scientists select these preparations because they provide von Willebrand factor, considered by a few to enhance inhibitor assay accuracy, however, the study demonstrates that these reagents may factitiously decrease the inhibitor recovery signal. The outcomes raise questions. Do lab scientists who manage FVIII inhibitor testing require or use FVIII deficient plasma with VWF, and if so, do they test for or request FVIII antigen levels from the manufacturer? The poster is now available for your download: Wood A, Kesavan N, Sadeghi-Khomami A, Black K, Boylan M, Ni R, Della Maestra J, Erb P, Foulon D, Hoogendoorn H. The Impact of Inactive FVIII Antigen in Factor VIII Deficient Plasma on the Measurement of FVIII Inhibitors.