Effect of coating concentrations of fibrinogen on adhesion of various α_Mβ₂-expressing cells. (A) Microtiter wells were coated with different concentrations (0-10 μg/mL) of fibrinogen (solid lines) or fibronectin (dashed line) for 3 hours at 37°C followed by coating afterward with 1% PVP. Adhesion of the α_Mβ₂-expressing HEK 293 cells (Mac-1), U937 cells, neutrophils, and macrophage IC-21 cells was determined as described in “Materials and methods.” The representative experiments for each cell type are shown. (B) The wells of Immulon 4BX microtiter strips were coated with different concentrations of ¹²⁵I-labeled fibrinogen (0.4-10 μg/mL with the specific activity 3.3 × 10⁴ cpm/μg). The wells were coated afterward with 0.5% PVP and washed with PBS. Radioactivity of the wells was measured as described in Figure 2. The data shown are the means ± SEs of 3 experiments with triplicate determinations in each experiment.