ADP is maintained in Fc-engineered anti-RhD mAbs. (A) The expression levels of FcγRI, FcγRII, and FcγRIII of THP-1 cells were measured by flow cytometry. (B) The gating strategy used for analysis of in vitro phagocytosis assays in the presence of non-RhD (top) or anti-RhD mAbs (bottom). (C) Phagocytic activity of mAbs at various concentrations. The phagocytosis score was calculated using the following formula: (% CTV⁺/pHrodo red⁺ cells × mean fluorescent intensity)/1000. The phagocytosis score of “no-Ab” control was subtracted from all samples. (D) Bar graphs depict the AUC of phagocytosis scores across varying mAb concentrations. The data presented show Ab concentrations ≤100 ng/mL. All the mAbs were tested alongside RhD-pIgG, but each group of mAbs is presented in a separate figure to allow for a clear comparison. Statistical analyses were conducted using 2-way ANOVA, followed by Dunnett multiple comparison test (GraphPad Prism v9). ∗∗∗∗P < .0001. Data are the average of 3 replicates, and error bars denote standard error of the mean (SEM). AUC, area under the curve.