[Studies on fibrinogen heterogeneity in disseminated intravascular coagulation]

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis utilizing a large pore gel showed that human fibrinogen (Fbg) in plasma resolved into 3 components which were tentatively designated as high molecular weight Fbg (HMW), low molecular weight Fbg1 (LMW1) and low molecular weight Fbg2 (LMW2) in order of their electrophoretic mobilities. Their estimated molecular weight were 360,000, 325,000 and 290,000 respectively. In normal plasma the ratio of HMW: LMW1: LMW2 was 71: 27: 2. Subunit chain analysis of Fbg species suggests that one of the A alpha chains in the predominant type of LMW1 is an A alpha remnant designated as A alpha', the molecular weight of which is about half that of the A alpha chain of HMW. The subunit chain formulas for the major forms of HMW and LMW1 are considered as (A alpha/1, 2)2 (B beta)2 (gamma)2 and (A alpha/1, 2) (A alpha') (B beta)2 (gamma)2 respectively. Although it is widely accepted that limited proteolysis of A alpha chain by plasmin might be the cause of Fbg heterogeneity, the conversion of HMW to LMW1 was not observed in the earliest stage of fibrinogenolysis induced by urokinase. However incubation of plasma induced the conversion of HMW to LMW1, even when t-aminomethyl-cyclohexane carboxylic acid or heparin was added to the plasma. These findings suggest that an unknown mechanism independent of plasmin or thrombin is responsible for the Fbg heterogeneity in blood. Clinically it is noticeable that the relative amount of LMW1 decreased markedly in disseminated intravascular coagulation (DIC). Animal models of DIC also exhibited essentially the same Fbg heterogeneity pattern as observed in DIC patients, when the levels of Fbg were recovering after the consumption caused by intravascular coagulation. In DIC it is considered that the consumption and compensatory production of Fbg results in the relative increase of HMW which is the freshly synthesized Fbg.