Involvement of CD47 in integrin-dependent T-cell adhesion. (A) The influence of 4N1K and a scrambled control peptide, at a concentration of 50 μM, on adhesion of activated blood T cells (90% of the adherent cells were CD3⁺) to fibronectin (20 μg/mL) and ICAM-1 (2 μg/mL). (B) 4N1K (50 μM) inhibits the enhancement of T-cell adhesion induced by anti-CD3 in T cells fresh from the blood. (C) Monoclonal antibodies to the CD47-binding C-terminal domain of TSP-1 (Ab-3) and to CD47 (B6H12), at a concentration of 2 μg/mL, inhibit spreading/pseudopodia formation in AF24 T cells on fibronectin (10 μg/mL). It is evident that in the presence of Ab-3 a high percentage of the cells were either not spread or showed a peripheral zone of flattened cytoplasm without pseudopodia. One representative experiment of 3 to 4 independent experiments is shown. Error bars: Statistics: Mann-Whitney U test (C).