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Effects of human elastase on von Willebrand factor in highly purified factor VIII concentrate and in cryoprecipitate
M Jeleńska1, W Bykowska, M Kopeć
1Institute of Haematology, Warsaw, Poland.
The susceptibility of v. Willebrand factor (vWF) and F.VIII in virus-inactivated factor VIII/vWF concentrate (Behring-Haemate-HS (BHS] and in cryoprecipitate (Behring-Ristofact) to digestion by highly purified, cathepsin G free human neutrophil elastase (HNE) was compared. In Haemate-HS HNE induced a degradation of the vWF subunit. This reaction was dependent on time and enzyme concentration. It resulted in disappearance of large size vWF multimers, an anodal shift of vWF peak in crossed immunoelectrophoresis and a decrease of F.VIII:C and Ristocetin cofactor activities. In contrast in cryoprecipitate even high HNE concentration did not provoke changes of these parameters. Both Haemate-HS and Ristofact were free of alpha 1-proteinase inhibitor (alpha 1 PI) and alpha 2-macroglobulin (alpha 2 M) but they differed in the content of other contaminating proteins. In particular Haemate-HS was fibrinogen-free but Ristofact contained 6.6 mg/ml. Purified fibrinogen added to Haemate-HS was found highly effective in protecting vWF in Haemate-HS against the proteolytic degradation and loss of activity under the influence of HNE.
The susceptibility of v. Willebrand factor (vWF) and F.VIII in virus-inactivated factor VIII/vWF concentrate (Behring-Haemate-HS (BHS] and in cryoprecipitate (Behring-Ristofact) to digestion by highly purified, cathepsin G free human neutrophil elastase (HNE) was compared. In Haemate-HS HNE induced a degradation of the vWF subunit. This reaction was dependent on time and enzyme concentration. It resulted in disappearance of large size vWF multimers, an anodal shift of vWF peak in crossed immunoelectrophoresis and a decrease of F.VIII:C and Ristocetin cofactor activities. In contrast in cryoprecipitate even high HNE concentration did not provoke changes of these parameters. Both Haemate-HS and Ristofact were free of alpha 1-proteinase inhibitor (alpha 1 PI) and alpha 2-macroglobulin (alpha 2 M) but they differed in the content of other contaminating proteins. In particular Haemate-HS was fibrinogen-free but Ristofact contained 6.6 mg/ml. Purified fibrinogen added to Haemate-HS was found highly effective in protecting vWF in Haemate-HS against the proteolytic degradation and loss of activity under the influence of HNE.