Heparin Precipitable Fraction (HPF, “Cryofibrinogen”) from Dermatological Patients

Heparinized plasma from certain dermatological patients mainly with psoriasis arthropathica demonstrated a precipitable fraction (HPF) when left at 4° C for 12 hours. The yield of isolated HPF-protein was 1.5-6.5 mg per ml of plasma, the clottability being of about 50-85 per cent. HPF consisted of three main components, fibrinogen, albumin and an unidentified protein (X-component). SDS polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol demonstrated the fibrinogen subunit chains to be of normal molecular weights. Quantitative N-terminal analysis demonstrated insignificant amounts of N-terminal glycine, indicating at most traces of soluble fibrin in the isolated HPF. Out of 21 patients with HPF 18 showed a negative ethanol gelation test in plasma, and 17 had no detectable FDP in serum.

The X-component was separated from albumin, subsequent to the removal of fibrinogen by heat precipitation (56° C-10 min), as a precipiatating complex with concanavalin A and could be separated from this by a gel filtration on Sephadex G 150 after dissolution of the complex in 0.5 M α-methyl-D-glucoside/0.3 M NaCl.

A possible interpretation is that HPF consists of a complex between essentially normal fibrinogen and the unidentified X-component with albumin as a main contaminant. The nature of the X-component and its quantitation in plasma in normal and pathological conditions are under study.