Recombinant Factor VIII (FVIII) products represent a life-saving intervention for patients with hemophilia A. However, patients can develop antibodies against FVIII that prevent FVIII function and directly increase morbidity and mortality. The development of anti-FVIII antibodies varies depending on the type of recombinant product employed, with previous studies suggesting that 2nd generation baby hamster kidney (BHK)-derived FVIII products display greater immunogenicity than 3rd generation Chinese hamster ovary (CHO)-derived FVIII. However, the underlying mechanisms responsible for these differences remain incompletely understood. Our results demonstrate that BHK cells express higher levels of the non-human carbohydrate a1-3 galactose (aGal) than CHO cells, suggesting that aGal incorporation onto FVIII may result in anti-aGal antibody recognition that could positively influence the development of anti-FVIII antibodies. Consistent with this, BHK-derived FVIII exhibits increased levels of aGal, which corresponds to increased reactivity with anti-aGal antibodies. Infusion of BHK-derived, but not CHO-derived, FVIII into aGal knock out mice, which spontaneously generate anti-aGal antibodies, results in significantly higher anti-FVIII antibody formation, suggesting that the increased levels of aGal on BHK-derived FVIII can influence immunogenicity. These results suggest that post-translational modifications of recombinant FVIII products with non-human carbohydrates may influence the development of anti-FVIII antibodies.
Connie M Arthur, Patricia E Zerra, Sooncheon Shin, Jianmei Wang, Xeuzheng Song, Christopher B Doering, Shannon Meeks, Pete Lollar, Sean R Stowell