Summary
Samples taken at various stages of preparation of intermediate purity factor VIII
concentrate were assayed for factor VIII coagulant activity (VIII:C), factor VIII
coagulant antigen (VIIIC: Ag) and factor VIII related antigen (VIIIR: Ag). The antigen
results were used to assess mechanical loss during fractionation as these markers
are relatively stable. In contrast VIII:C is sensitive to both mechanical and inactivation
losses.
The major loss of factor VIII occurred during the cryoprecipitation and extraction
step and was due to both mechanical loss and inactivation. Losses before and after
this step were largely due to inactivation of the factor VIII.
Assay of VIIIR: Ag in concentrates presented problems and a modified technique is
suggested.
Keywords
Factor VIII Concentrates - Plasma fractionation