Activation of the kallikrein system in hyperbetalipoproteinemia.

: In 30 patients with hyperlipoproteinemia (19 type II and 11 type IV), the role of the intrinsic coagulation pathway was evaluated by assays of preK, Kl's, and Hageman factor (factor XII). Analysis of the plasma of type II patients suggested activation of the intrinsic pathway characterized by a 40% decrease in preK (p less than 0.01) and a 50% decrease Kl (p less than 0.01); in contrast, analysis of the plasma of type IV patients showed no activation of the intrinsic pathway. In type II patients C-1INH was present in normal concentrations as measured by immunochemical techniques. The findings of normal levels of C-1INH by immunoassay, in association with altered electrophoretic mobility, are suggestive of formation of a kallikrein-C-1INH complex in vivo.