Production and characterization of a murine monoclonal antibody against a heavy chain of Hageman factor (factor XII)

Abstract

A murine hybridoma cell line that produces a monoclonal antibody to human Hageman factor (HF, factor XII) is described. The antibody (P 5-2-1) consists of mouse IgG(2b) heavy chains and λ light chains, selectively neutralizes HF procoagulant activity, and prevents the proteolytic cleavage of HF during contact activation in plasma. When HF is exposed to P 5-2-1 before the absorption of HF to kaolin, HF procoagulant activity is markedly inhibited. In contrast, P 5-2-1 does not interfere with HF activity after the adsorption of HF to kaolin. P 5-2-1 does not inactivate the prekallikrein-activating activity of 28,000-mol wt HF fragments (HF(f)). P 5-2-1 binds exclusively to the 40,000-mol wt portion of a heavy chain of HF and inhibits the adsorption of HF to negatively charged surfaces. P 5-2-1 immobilized to Sepharose can be used to deplete HF from normal human plasma. This immunoaffinity-depleted plasma is indistinguishable from congenital HF-deficient plasma and can be used as the substrate for HF procoagulant activity assay.