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. 1974 Sep 1;140(3):797-811.
doi: 10.1084/jem.140.3.797.

Direct evidence for Hageman factor (factor XII) activation by bacterial lipopolysaccharides (endotoxins)

D C Morrison, C G Cochrane

Direct evidence for Hageman factor (factor XII) activation by bacterial lipopolysaccharides (endotoxins)

D C Morrison et al. J Exp Med. .

Abstract

Purified precursor Hageman factor has been demonstrated to bind to soluble bacterial lipopolysaccharide (LPS, endotoxin) isolated from Escherichia coli 0111:B4, and this complex has been shown to have the capacity to convert prekallikrein to its active form. In addition, LPS-activated Hageman factor substantially reduces clotting times in XII-deficient plasma. The capacity to activate Hageman factor has been demonstrated to reside in the lipid A region of the LPS molecule. Activation of Hageman factor by LPS contrasts with fluid-phase activation (e.g., by kallikrein or trypsin) in that no cleavage to lower molecular weight fragments occurs. High concentrations of LPS inhibit the activity of Hageman factor, probably by a direct LPS-Hageman factor interaction.

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