Activation of Hageman factor by lipopolysaccharides of Bacteroides fragilis, Bacteroides vulgatus, and Fusobacterium mortiferum.

Preincubation of lipopolysaccharides (LPS) of Bacteroides fragilis, Bacteroides vulgatus, and Fusobacterium mortiferum with purified human Hageman factor (HF) followed by addition of purified human prekallikrein resulted in the activation of HF, as measured by the generation of kallikrein using the tripeptide substrate N-alpha-benzoyl-L-proline-L-phenylalanine-L-arginine-4-nitroanilide. Addition of purified HF, which had been preincubated with the LPS, to HF-deficient plasma resulted in the acceleration of the recalcification time. Addition of the LPS to HF-deficient plasma reconstituted with various concentrations of HF also resulted in the acceleration of the recalcification time; the magnitude of the acceleration correlated with the amount of HF used to reconstitute the deficient plasma. These results demonstrate that LPS of selected gram-negative anaerobes activate HF and thereby initiate the intrinsic pathway of coagulation.