As all commercial factor VIII concentrates in current use have been subjected to some
form of virus-inactivation, we wanted to compare their in vitro biochemical characteristics.
Of the 10 concentrates studied, inactivation takes the form of dry heat treatment,
varying from 60°C for 30 h to 72°C for 68 h, in six products (Octonativ, KabiVitrum;
Hemofil T, Hyland; Factorate HP, Armour - heated two different ways; Monoclate, Armour;
Nordiocto, Nordisk Gentofte). In the 4 remaining concentrates, inactivation is either
by steam treatment (Kryobulin Tim 3, Immuno), heating at 60°C for 20 h as dry material
slammed in heptane (Profilate, Alpha), wet-heating at 60°C for 10 h (Hemate, Behring),
or by the New York Blood Center (solvent/detergent) method (OCTA-V. I., Octopharm).
The variables studied were VIII:C by one-stage and chromogenic assay, and VI11 :Ag,
vW:Ag, by electroimmunoassay, immunoradiometric assay (IRMA), crossed immunoelectrophoresis
and SDS agarose gel electrophoresis followed by staining with radioactive antibody
and fibrinogen. VIII :C activity values ranged from 20-53 IU/ml in all products but
Monoclate (94 IU/ml). All products gave higher values of VIII:Ag than of VI11 :C,
indicating partial inactivation of VIII :C during preparation; the ratios ranged from
1.2 to 1.3 for Kryobulin, Nordiocto, OCTA-V. I., and Hemofil T, and from 2 to 4 for
the other products, being highest in Profilate and Monoclate. Specific activity was
higher in Monoclate, Nordiocto, Hemate, OCTA-V. I. and Factorate HP (16.0, 7.4, 7.1,
4.8 and 3.3 IU/ml protein, respectively) than in the other products (1.3-2.3 IU/mg).
All concentrates contained vW:Ag, and non-parallel dose-response curves indicated
abnormality in the vWF molecule in all cases; and thus multimeric sizing failed to
demonstrate the largest multimers of the vWF in any product. We conclude that although
virus-inactivated F VIII concentrates are general ly comparable with regard to VIII
:C content, they vary considerably in the degree of VIII :C inactivation during preparation,
and in specific activity. No concentrate tested here contained native vWF. In vivo
studies have shown VIII :C recovery and half-life to be comparable in heat-treated
and non-heat-treated concentrates.
