The immunodepletion of factor VII from human plasma using a monoclonal antibody

A murine hybridoma cell line which secretes monoclonal antibody to factor VII has been prepared to facilitate the immunodepletion of this clotting factor from plasma. Specific monoclonal antibody was purified from mouse ascites tumours by protein A-Sepharose chromatography and shown to be of the IgG1 immunoglobulin subclass. On immunoblotting, this antibody reacted with a single protein band identical to purified factor VII. The purified monoclonal antibody was coupled to Sepharose 4B and was used to immuno-deplete factor VII from pooled normal human plasma. The prothrombin time of plasma immunodepleted in this way was 35 s compared to 12 s for the starting plasma. Specific factor assays of the immunodepleted plasma showed factor VII activity to be less than 1% while the levels of the other clotting factors were unchanged. The immunodepleted plasma was equivalent to severe congenital factor VII deficient plasma as a substrate for factor VII assays. Bound factor VII could be eluted from the immunoaffinity column with citrate buffer, pH 6.0, with good recovery.