Figure 4.

Coaggregation of FcγRI with CD13 increases the phagocytic capacity of monocyte‐derived macrophages from human donors. Cells were incubated with the indicated concentrations of anti‐FcγRI mAb with or without F(ab)′₂ fragments of anti‐CD13 mAb (10 μg) or with anti‐CD13 mAb alone (10 μg) for 30 min. After washing, incubation with EBS‐Ab was carried out at 37°C for 30 min. After lysis of noninternalized erythrocytes, the phagocytic index was determined by light microscopy. (A) Data represent the mean phagocytic index of cells from three different donors. (B) Data are presented as the relative phagocytic index, which corresponds to the ratio of the phagocytic index observed with the combination of the two mAb to the phagocytic index obtained with anti‐FcγRI mAb alone. The number close to each point corresponds to the fold increase attributable to CD13 co‐cross‐linking.