“…In addition to the evaluation of FVIII inhibitory activity, mAbs were characterised using a combination of methods, as reported previously [Gilles, J.G., et al, submitted]: (1) binding to ni trocellulose sheets blotted with native or thrombin-digested FVIII; (2) binding to polystyrene plates coated with native FVIII or purified heavy or light chain; (3) binding to FVIII insolubilised on vWF-or phosphatidylserine-coated plates; (4) cross-inhibition ELISA with mAbs Cag 117, Cag 69, CagA and Cag9 of the CLB series and of known specificity (obtained by courtesy of the Netherlands Red Cross) [15,16], and (5) immunoprécipitation with soluble recombi nant fragments of the A2, Cl and C2 domains of FVIII (carried out by Dr. Scandella, Rockville) as described [17]. Five antibodies from the ESH mAb series that did not cross-react with mAbs of our own pro duction were also used in the assay systems.…”