Apparent affinities of FVIII-specific antibodies assessed for individual immunoglobulin isotypes and IgG subclasses. Presented are apparent affinities K_A [M⁻¹] of FVIII-specific antibodies found in the different study cohorts presented in Figure 2. All samples containing FVIII-specific antibodies with a titer ≥1:80 as presented in Figure 2 were included in the analysis. (A) Patients with severe hemophilia A and FVIII inhibitors (HA-INH). (B) Patients with severe hemophilia A without FVIII inhibitors (HA-noINH). (C) Patients with acquired hemophilia A (Acqu-HA). (D) Healthy individuals (Healthy). Some samples in each study cohort contained 2 populations of FVIII-specific antibodies with distinct apparent affinities. These 2 populations present in the same sample are indicated by an open circle and a closed circle connected by a straight line.