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

Abstract

A heparin precipitable fraction (HPF) was obtained upon cooling (+4°C) of heparinized plasma from dermatological inpatients, mainly affected with psoriasis arthropathica. HPF, isolated by centrifugation (+4°C) and redissolved in 0.15 M NaCl at 37°C, consisted of about 60% thrombin-clottable protein. This portion could also be removed by heating at 56°C for 10 min. Polycrylamide gel electrophoresis demonstrated the larger part of HPF to be fibrinogen. In addition varying amounts of albumin and an unidentified protein (X-component) and traces of other plasma proteins were observed. SDS gel electrophoresis demonstrated the fibrinogen-related protein to have the same molecular weight as purified human fibrinogen. Upon reduction with beta-mercaptoethanol only intact Aα, Bβ and γ-chains were observed. Quantitative N-terminal amino acid analysis showed insignificant amounts of N-terminal glycine indicating the absence of soluble fibrin. Eighteen out of 21 patients with HPF had a negative ethanol gelation test in citrated plasma, and 17 out of 21 patients demonstrated no detectable serum FDP. Possibly, HPF exists in plasma as a complex between native fibrinogen, the X-component and heparin.