Heparin precipitable fraction (HPF) from dermatoligical patients. I. Characterization of the thrombin-clottable protein

A delaying influence of cryoglobulins in the assessment of euglobulin fibrinolytic activity

The presence of cryoglobulin in plasma was found to interfere with the assessment of euglobulin fibrinolytic activity. Cryoglobulins co-precipitate with the isoelectrically precipitated euglobulins thereby giving rise to erroneous determinations of components of the extrinsic and intrinsic fibrinolytic systems. Cold-promoted activation of the F XII-dependent part of the intrinsic proactivator system was related to the presence of cryoglobulins. Strictly optimized procedures for the preparation of euglobulin solutions are essential in the accurate determination of euglobulin fibrinolytic activity. Resuspended euglobulins should be kept for at least 30 min at 0 degree C followed by at least 2 min at 37 degrees C in order to secure conditions yielding accurate and reproducible assays of activity in samples of patient plasma.

Evidence that changes in fibrinogen quality during acute phase reactions are of major importance for the amount of heparin precipitable fraction (HPF)

The influence of qualitative and quantitative changes in plasma fibrinogen upon the amount of heparin precipitable fraction (HPF), obtained during the course of acute disease states, were examined. Whereas fibrinogen in plasma includes 3 species of different molecular weights (HMW, LMW, LMW'), fibrinogen in HPF, from normal as well as from "acute phase" plasma, consisted almost exclusively of HMW-fibrinogen (3% SDS-PAGE). Sub-unit chain electrophoresis (10% PAGE-SDS and two-dimensional electrophoresis) did not disclose any signs of abnormalities in the fibrinogen precipitated in HPF. Studies on patients revealed that the composition of plasma fibrinogen changed (increased HMW) during the course of acute myocardial infarction and following hip operations, and indicated that the amount of HPF was governed by the relative amount of HMW-fibrinogen as well total fibrinogen. This assumption was strengthened by quantitating the amount of HPF obtained after addition of highly purified HMW and LMW fibrinogen to normal and "acute phase" plasma. It is concluded that fibrinogen quality (per cent HMW or HMW/LMW ratio) is of major importance for the amount of HPF, thereby explaining some of the HPF-variations seen during the course of acute diseases.

Does qualitatively altered fibrinogen contribute to the increased heparin precipitable fraction (HPF) in acute myocardial infarction (AMI)?

The amount and protein composition of heparin precipitable fraction (HPF), and the plasma concentrations of fibrinogen, fibronectin, alpha 1-acid glycoprotein, alpha 1-antitrypsin, haptoglobin and C-reactive protein (CRP) were determined in healthy subjects as well as during the course of acute myocardial infarction (AMI). In all samples tested, HPF consisted nearly exclusively of fibrinogen and fibronectin. In the small precipitates from healthy subjects, approximately equal amounts of these two proteins were recovered. During the first days of AMI, plasma fibrinogen increased 2-3 fold. At the same time, however, the amount of HPF increased 5-10 fold. This increase was associated with increased precipitation of fibrinogen, whereas no simultaneous increase in fibronectin was found. In fact, a slight drop in plasma as well as HPF-fibronectin was regularly observed during this period. During the following week HPF returned to normal values, whereas the plasma fibrinogen remained elevated. No satisfactory explanation for this discrepancy can be offered at present. Thus, no evidence could be provided that other acute phase proteins than fibrinogen itself were involved. Some experiments, however, indicated qualitative changes in the fibrinogen participating in the HPF precipitation. Further studies are necessary to clarify this point. Such studies are in progress.