Macrophages adhere to the CEP-modified proteins via β₂integrins. (A-B) Peritoneal macrophages. Ninety-six-well plates were coated with different ligands for 3 hours at 37°C. (A) Fluorescently labeled macrophages were added to the wells and cell adhesion was determined after 30 minutes in a fluorescence plate reader. (B) Some samples were preincubated with anti-β₂ and anti-β₁ blocking antibodies before the adhesion assay.**P < .01. (C-F) HEK 293–transfected cells. (C) α_Mβ₂, α_Dβ₂, and α_Lβ₂-HEK 293 transfected cells were generated as described in the “Materials and methods” section and tested by flow cytometry analysis. The mock-transfected cells are shown only with anti-α_M mAb. A similar result was obtained with anti-α_L and anti-α_D antibodies. Ninety-six-well plates were coated with CEP (D) or different ligands (E-F) for 3 hours at 37°C. α_Mβ₂, α_Dβ₂, α_Lβ₂, or mock-transfected cells were labeled with 10 µM Calcein AM. (E-F) For some experiments, cells were preincubated with anti-integrin blocking antibodies. In separate wells, immobilized CEP-BSA was preincubated with anti-CEP mAb. After incubation, cells were added to the wells and cell adhesion was determined after 30 minutes in a fluorescence plate reader. Statistical analyses were performed using Student t test. Fn, fibronectin.