Studies on Components of the plasma kallikrein-Kinin System in Normal Subjects and Patients with Septicemia

Abstract

Over the past decade evidence that the plasma kallikrein-kinin system is activated during septicemia has accumulated. We have used several tests, including newly developed chromogenic peptide substrate assays, to study components of this proteolytic enzyme system in plasma samples from normal subjects and patients with septicemia. The parameters studied were Hageman factor(HF), plasma kallikrein (KK), plasma prekallikrein (PKK), high molecular weight kininogen(HMwK), functional kallikrein inhibition (KKI), c1-esterase inhibitor (CIINH) , α2-macroglobulin (α2 M)and α1-antitrypsin (α1AT ). In samples from patients with fatal sepsis, levels of HF, PKK, HMwK, α2M and KKI were all markedly reduced and spontaneous KK activity was detected. CIINH and α1AT levels were much higher than normal. In plasma samples from three patients with septicemia who subsequently recovered mean plasma levels of PKK, KKI, HMwK and CIINH were higher than in the samples from the patients who died. Our results emphasize that the plasma kallikrein-kinin system becomes activated during septicemia and suggest that functional kallikrein inhibition contributes to survival.