Adhesion of CHO cells expressing IIb^P145Aβ3 to immobilized fibrinogen.

(A) CHO cells were co-transfected with either wild-type αIIb or αIIb^P145A and β3. Untransfected cells (Un'Tx), cells expressing wild-type αIIbβ3 (wild type), and cells expressing αII^P145Aβ3 (mutant) were sorted by flow cytometry with the use of the anti-β3 monoclonal antibody SSA6. Comparable expression of αIIbβ3 on the transfected cells was confirmed with the use of the anti-αIIb monoclonal antibody B1B5 and the anti-β3 monoclonal antibody PT25-2. (B) Adhesion of untransfected CHO cells (open bars) and CHO cells expressing comparable levels of either wild-type αIIbβ3 (shaded bars) or αIIb^P145Aβ3 (solid bars) to immobilized fibrinogen was measured in the absence or presence of the αIIbβ3-activating β3-specific monoclonal antibody PT25-2. Reduction of adhesion to baseline levels by 1 mM EDTA indicates that adhesion to fibrinogen was integrin-specific. The data show the mean ± SD that was done in 3 separate runs.