Summary
A high yield, intermediate purity factor VIII concentrate derived from heparinized
plasma has been developed which can be heat-treated at 60 °C, 68 °C or 80 °C/72 h
to permit inactivation of viral contaminants which may be present. After cold reprecipitation
of the heparinized cryoprecipitate (CRC), the resolubilized CRC precipitate was adjusted
to 25-30 mg/ml protein and pH 6.35 ± 0.1 and incubated for 1 h at 8 °C. After centrifugation
to remove the precipitated fibrinogen and fibronectin, a factor VIII-rich supernatant
can be recovered which contains > 500 units of VIII : C per liter of starting plasma
(Method I product) at a purity of 1.5 U/mg protein. Adjusted to 50 mM glycine and
pH 6.8, the product can be lyophilized and heat-treated at 60 °C/72 h without a significant
loss of VIII :C activity. However, at 68 °C or 80 °C/72 h, temperatures now reported
to be more effective in viral inactivation, the recoveries were reduced to 68 and
33% respectively. Significantly improved recoveries after heat-treatment (HT) at 68
°C or 80 °C/72 h were achieved if the 8 °C supernatant product was prepared by a modified
procedure (Method II). This further reduces the fibrinogen content of the product
while maintaining VIII : C yields > 500 U/l at a purity of 1.9 U/mg. When adjusted
to 50 mM glycine and 1-2% (w/v) sucrose (pH 6.8), lyophilized and heat treated at
60 °C, 68 °C or 80 °C/72 h, the VIII :C recoveries of Method II product were 88-100%,
79-84% and 80-83% of pre-HT levels respectively. The yield of VIII : C was > 400 U/l
at a purity of 1.6-1.4 U/mg at 1-2% (w/v) sucrose even after the severe heat-treatment
at 80 °C. In addition, the von Willebrand factor multimers are similar in size and
triplet pattern to those observed in routine cryoprecipitate preparations.
