Cell adhesion to SIRPα1ex and SIRPα2ex, but not to SIRPβ1ex.

SIRP fusion proteins (2 μL of 20 μg/mL solutions) were immobilized on nitrocellulose-coated Petri dishes by air-drying. Adhesion of Jurkat cells to SIRPα1ex, SIRPα2ex, and SIRPβ1ex was analyzed by incubating the cells for 1 hour at 37°C, as described.17Specific cell binding is shown in the round protein drop and was evaluated and photographed using a Zeiss Axiovert microscope (original magnification × 40; n = 3). SIRPα adhered to all tested CD47⁺ cell lines (HL-60, KG1a, K562, MO7e, 207, Daudi, CCRF-CEM, Molt-4, EM2, U937, and LAMA-84); adhesion of SIRPβ was always negative.