Molecular modifications in factor VIII concentrates produced from different plasma pools.

Area of Science:

• Hematology
• Immunology
• Biochemistry

Background:

• Hemophilia A patients treated with factor VIII (fVIII) concentrates can develop inhibitory antibodies.
• Previous research suggested viral inactivation methods, specifically solvent/detergent (S/D) treatment and pasteurization, contributed to fVIII concentrate immunogenicity.
• Elevated coagulation markers in plasma pools were noted in concentrates associated with higher immunogenicity.

Purpose of the Study:

• To identify the primary cause of increased immunogenicity in commercial fVIII plasma-derived concentrates.
• To investigate whether the plasma source or viral inactivation processes induce structural changes in the fVIII C2 domain, leading to antibody formation.

Main Methods:

• Analysis of fVIII concentrate samples from different plasma pools.
• Assessment of binding affinity to phospholipids.
• Evaluation of binding to conformationally sensitive anti-C2 domain antibodies.

Main Results:

• fVIII concentrates from abnormal plasma pools exhibited reduced binding to phospholipids and specific anti-C2 antibodies.
• These binding defects were most significant in concentrates treated with both S/D and pasteurization.
• Structural alterations in the fVIII C2 domain were linked to the quality of the starting plasma pools.

Conclusions:

• Insufficient quality of starting plasma pools is the principal determinant of structural alterations in the fVIII C2 domain.
• The combination of S/D treatment and pasteurization exacerbates these detrimental structural changes.
• This study reframes the understanding of fVIII concentrate immunogenicity, highlighting plasma quality as the key factor.