The effect of the physicochemical state of factor VIII on its interaction with human antibodies

To assess the effect of the physicochemical state of factor VIII on its interaction with human antibodies, this interaction was examined using buffer conditions which would insure dissociation of the factor VIII complex. Anti-factor VIII titers were increased 2 to 2.5 fold under such conditions. When isolated factor VIII procoagulant material was used as the antigen source, the antibody titers were increased but no difference was noted in the presence or absence of the high ionic strength buffers. These studies indicate that factor VIII-related antigen in some manner retards the interaction of the procoagulant portion of factor VIII with human antibodies and may explain the peculiar time-dependence of factor VIII inactivation by these antibodies.