Quantitative abnormality of an Aalpha chain molecular weight form in the fibrinogen of cirrhotic patients.

The molecular weight heterogeneity of fibrinogen from the whole plasma of 12 normal and seven cirrhotic individuals was examined by means of a novel two-dimensional sodium dodecyl suphate (SDS) gel electrophoretic technique. Fibrinogen was first separated from other plasma proteins on a large pore gel, cut out of the gel, reduced, and separated into its component Aalpha, Bbeta and gamma chains on a second gel. Fibrinogen was resolved into two major bands, I and II, on the first gel. The ratio of fibrinogen II to fibrinogens I plus II was approximately 0.3 (range 0.2-0.35) for both normals and cirrhotic patients. Two major molecular weight (mol wt) forms of Aalpha chain were present in normal fibrinogen I: Aalpha/I and/or Aalpha/2, mol wt 7 X 10(4) and 6.7 X 10(4) respectively. Normal fibrinogen II contained either one of these Aalpha chains plus one of the smaller Aalpha chains, Aalpha/6--10, accounting for the 3--4 X 10(4) mol wt difference between bands I and II. Aalpha/2 comprised 33% of the total Aalpha chains (range 27--41%) in normal fibrinogen I and approximately 25% of the Aalpha chains in normal fibrinogen II. In contrast, fibrinogen I from six out of the seven patients contained a lower percentage of Aalpha/2 (range 10--25%). Similarly fibrinogen II from these patients was deficient in Aalpha/2, although the protein contained normal levels of lower mol wt Aalpha derivatives. No correlation was found between per cent fibrinogen II and per cent Aalpha/2 in either normal or cirrhotic subjects. These results suggest that at least two independent processes are responsible for the observed levels of Aalpha heterogeneity in normals and cirrhotics and that the process controlling Aalpha/2 production is a abnormal in cirrhotic individuals. This decrease in Aalpha/2 does not affect the coagulability of fibrinogen. Fibrin monomer aggregation studies indicate that a serum component is, in part, responsible for the abnormally transparent clot formed from the plasma of cirrhotics.