Fig. 3.

BC31M4 blocks the cell-surface CD47-SIRPα interaction and promotes macrophages phagocytosis of tumor cells. a Top, the binding and blocking activity of antibodies to different tumor cells at pH 7.4 and pH 6.8. Bottom, the calculated EC₅₀ and IC₅₀ for the data of the top panel. “~” indicates estimated values; “-” indicates EC₅₀ or IC₅₀ values are not measurable. b, c Macrophages phagocytosis of Raji cells induced by different antibodies at pH 7.4 and pH 6.8. All antibodies used are of hIgG1 isotype except BC31M4-F(ab′)₂. Antibody concentration is 1 μg/ml for Rituximab, and 5 μg/ml for BC31M4 and BC31M4-F(ab′)₂. Phagocytosis index is determined as the number of phagocytosed Raji cells per 100 macrophages. d Schematic diagram of tumor inoculation and antibody treatment in human tumor xenograft models. e Tumor growth of mice treated as in (d). f Survival of mice in (e). n, number of mice