Fig. 4.

Flow cytometric analysis of binding activity of mAb^P and mAb^M BR55-2 to the FcγRI receptor. (A) U937 cells treated with IFN-γ to stimulate Fc receptor expression were incubated with mAb^P or mAb^M BR55-2 or CD64-specific mAb m22-FITC. Binding activity of mAb^P (Left), mAb^M (Center), and m22-FITC (Right) to the activated cells expressing CD64 were analyzed by flow cytometry. Black and gray lines indicate binding of mAbs before or after blocking treatment of human serum, respectively (Left and Center) or indicate cells treated with m22-FITC or an mAb isotype control (Right). (B) 3T3 cells were transfected with CD64 cDNA and treated with mAb^P BR55 (Left), mAb^M BR55 (Center), or mAb m22-FITC (Right). Black and gray lines indicate transfected or mock-transfected cells bound by each mAb, respectively.