Longitudinal monitoring of FVIII-binding antibodies and FVIII inhibitors in 2 representative examples of patients in subgroup 2. (A-B) Results of the analysis of FVIII-binding antibodies (IgG1, IgG2, IgG3, IgG4, IgA, and IgM, as indicated) and FVIII inhibitors (BU/mL) for 2 representative examples of patients in subgroup 2, patient 9 (A) and patient 14 (B), who developed FVIII-binding IgG1 antibodies but did not develop FVIII inhibitors throughout the study period. The red dotted lines represent the limit for positive evaluation of FVIII inhibitors (0.6 BU/mL). (C-D) Apparent affinity constants of FVIII-binding IgG1 antibodies (mean K_A) and FVIII inhibitors (BU/mL) in patient 9 (C) and patient 14 (D). Data for apparent affinity constants include the 95% CIs for up to 2 IgG1 affinity clusters (open blue bars, IgG1 population 1; closed blue bars, IgG1 population 2). The red dotted lines represent the limit for positive evaluation of FVIII inhibitors (0.6 BU/mL). K_A, apparent affinity constant. The data for the remaining 5 patients of subgroup 2 are shown in supplemental Figure 3.