[The fibrin and plasma-protein content of human thrombi]

The protein composition of cell-free thrombus contained in abdominal aneurysms of the aorta was investigated using PAGE and immunoreactivity after solubilization. 1. The dry weight was 18--29%, with minor differences between various locations. 2. 35--40% of the dry weight was extractable with NaCl/citrate and was identified as albumin (80%) and IgG (15%). Trace amounts of fibrinogen immunoreactive material were present. 3. The NaCl/citrate insoluble part was 80% hydrolyzable with plasmin. The predominant fragment was D-D dimer (from cross-linked fibrin). In addition, fragments Dand E were observed. Reduction of the NaCl/citrate insoluble part with 2-mercaptoethanol resulted in almost complete solubilization. PAGE analysis demonstrated alpha-polmers, gamma-gamma dimers and little free alpha-chains, indicating almost complete cross-linking of fibrin. Thus, the major protein were cross-linked fibrin, albumin and IgG.