Native-like aggregates of Factor VIII (FVIII) are immunogenic von Willebrand Factor deficient and hemophilia A mice

Abstract

The administration of recombinant Factor VIII (FVIII) is the first line therapy for Hemophilia A (HA), but 25–35% of patients develop an inhibitory antibody response. In general, the presence of aggregates contributes to unwanted immunogenic responses against therapeutic proteins. FVIII has been shown to form both native-like and non-native aggregates. Previously, we showed that non-native aggregates of FVIII are less immunogenic compared to the native protein. Here we investigated the effect of native-like aggregates of FVIII on immunogenicity in HA and von Willebrand Factor knockout (vWF−/−) mice. Mice immunized with native-like aggregates showed significantly higher inhibitory antibody titers compared to animals that received native FVIII. Following re-stimulation in vitro with native FVIII, the activation of CD4+ T cells isolated from mice immunized with native-like aggregates is ~4 fold higher than mice immunized with the native protein. Furthermore, this is associated with increases in the secretion of pro-inflammatory cytokines IL-6 and IL-17 in the native-like aggregate treatment group. The results indicate that the native-like aggregates of FVIII are more immunogenic than native FVIII for both the B cell and T cell responses.