Figure 3. FcαRI-binding and recruitment of myeloid effector cells. In (A), binding of 225-IgA2-wt and –d471 to BHK-21 cells co-transfected with human FcαRI and FcRγ was measured by indirect immunofluorescence using FITC-labeled anti-human kappa light chain directed secondary antibody. Efficiency of IgA2 antibodies in mediating ADCC against A431 targets cells was analyzed in⁵¹chromium release assays using whole blood and increasing antibody concentrations (B). Next, increasing volumes of whole blood (C) and increasing ratios of isolated granulocytes (D), monocytes (E) and monocyte-derived macrophages (F) were used as effectors cells. Results are shown as “mean ± SEM” of “FcαRI binding [RFI %]” (A) or “specific lysis [%]” (B–F) of at least five independent experiments. Significant differences between EGFR-specific and control antibodies (control IgG1 in [A], control IgA2 in [B‒F]) are indicated by * (P ≤ 0.001).