Biochemical properties of Factor VIII (FVIII) in highly-purified FVIII concentrates (CROSS EIGHT M) produced by monoclonal antibody column were studied and compared with those of Hemofil M which was already used clinically. The FVIII clotting activity (FVIII:Cclot) levels obtained by one-stage method using severe hemophilia A plasma as a substrate were 614-729U/vial and identical with those indicated on the label (500U/vial). The FVIII light chain antigen (FVIIIL:Ag) levels measured by Enzyme Immunoassay were 540-760U/vial. The ratio of FVIIIL:Ag to FVIII:Cclot (FVIIIL:Ag/FVIII:Cclot) were 0.88-1.04. The ratio of FVIIIL:Ag to von Willebrand Factor antigen (vWF:Ag) (FVIIIL:Ag/vWF:Ag) were 49.0-60.8. No difference was observed between CROSS EIGHT M and Hemofil M on the FVIII:Cclot levels, FVIIIL:Ag levels, FVIIIL:Ag/FVIII:Cclot and FVIIIL:Ag/vWF:Ag.
SDS-PAGE patterns showed almost no contamination except albumin being added as a stabilizer. Western blot analysis revealed FVIII heavy chain antigen of M. W. 90kDa-220kDa and FVIII light chain antigen of M. W. 80kDa. No degradates of MW. 43kDa-50kDa derived from FVIII heavy chain antigen were observed. CROSS EIGHT M lacked the large multimers of vWF which were detected in normal human pooled plasma. No difference was observed between CROSS EIGHT M and Hemofil M by western blot analysis of FVIII and multimer analysis of vWF.
These results suggest that CROSS EIGHT M preserves the fundamental structure of FVIII molecule for coagulant activity. Therefore, CROSS EIGHT M as well as Hemofil M may be clinically used with safety as FVIII concentrates.
