Fig. 3.

Afucosylated IgG-specific nanobodies block Fc–FcγR interactions in vitro and in vivo. (A) Epitope mapping by SPR shows mutually exclusive binding of B7 and FcγRIIIA to afucosylated IgG1. Vertical dashed lines indicate primary and secondary injection times. (B and C) ELISA evaluating nanobody inhibition of FcγRI or FcγRIIIA binding to afucosylated IgG or immune complexes, respectively. Data displayed as mean ± SEM. Data were fitted by nonlinear regression analysis. (D and E) Mice were coadministered X0-Fc (2.5 mg/kg) and rituximab G2 (0.5 mg/kg) either prophylactically or as treatment. Data displayed as mean ± SEM (n = 3–4 mice per group).