Soluble SIRPβ2 specifically binds cells expressing CD47. Gray profiles represent binding of SIRPβ2-D1D2-IgG (left column) or SIRPα-D1D2-IgG (right column) to Jurkat (top row) and Jurkat-CD47⁰ (middle row). Thin solid lines indicate background staining of Jurkat and Jurkat-CD47⁰. (Bottom row) Bar graphs represent binding of SIRPβ2-D1D2-IgG (left panel) or SIRPα-D1D2-IgG (right panel) to Jurkat in the presence of mAbs against CD47 (maximal inhibition), SIRPα (148), SIRPβ2 (LSB2.20; partial inhibition), SIRPβ1 (LSB1.50), and control mAb (no inhibition). Bar graphs presented here represent one of 4 independent experiments with similar results. MFI indicates mean fluorescence intensity.