Activation of Hageman factor (factor XII) by sulfatides and other agents in the absence of plasma proteases

Incubation of purified human HF (factor XII) with sulfatides, EA, kaolin, or glass resulted in the generation of amidolytic activity in the apparent absence of other enzymes. Sulfatides or EA rapidly and efficiently initiated intrinsic coagulation in normal plasma but, under the conditions tested, only trivially corrected the prolonged partial thromboplastin clotting times of plasma deficient in prekallikrein or HMWK. Preliminary incubation of HF with crude IgG directed against plasma kallikrein or SBTI did not influence the results. The presence of albumin greatly enhanced activation of the amidolytic properties of purified HF by EA, even when albumin had been lipid-extracted or treated with DFP or SBTI; albumin also increased activation of HF by sulfatides. Internal cleavage and minimal scission of the HF molecule accompanied the generation of amidolytic properties in mixtures of HF and sulfatides; cleavage was not blocked by SBTI. These experiments demonstrate that negatively charged substances can activate HF in absence of other enzymes and that this activation is accompanied by formation of a two-chain species of HF.