VWF impairs FVIII-IC binding to Fc-γ receptor on APCs. (A) Representative flow cytometry histograms of FVIII-IC binding to murine BMDC, confirming the Fc-γ receptor–dependent binding mechanism. FVIII-ICs were generated by mixing of 7 AF647-labeled monoclonal anti-FVIII antibodies (Ab1-7; refer to Table 1) and rhFVIII. BMDCs without staining served as negative control (Neg Ctrl.). (B) Normalized binding of FVIII-ICs to BMDCs. Preincubated molecules are indicated by round parentheses. The data represent the mean fluorescence intensity (MFI) of the respective sample divided by the MFI of IC (rhFVIII + Ab1-7), multiplied by 100. The mean values ± SD obtained from 4 independent experiments done in duplicates are shown. For the (rhFVIII + HSA) + Ab1-7 sample, 3 independent experiments were performed in duplicates. The statistical comparison was made using 1-way ANOVA with Bonferroni multiple comparisons test. Statistical significance: ∗P < .05. ns, not significant.