Triggering of CD47-dependent T-cell adhesion through the N-terminal domain of TSP-1. (A) Stimulation of adhesion and spreading of AF24 T cells on collagen type IV and fibronectin by CRT19-36, at a concentration of 50 μM. Flattened cells (phase dark) with pseudopodia dominate among cells treated with CRT19-36, whereas spherical cells (phase bright) dominate in controls (hep2). The top right panels show enhancement of TSP polarization in cells with CRT19-36. (B) 4N1K inhibits T-cell adhesion induced by CRT19-36; both peptides used at a concentration of 50 μM. (C) An anti–β1-integrin antibody (CD29, 4 μg/mL) inhibits adhesion and spreading of AF24 T cells on fibronectin (10 μg/mL) induced by CRT19-36 as determined after 15 minutes. A control peptide, hep1, did not stimulate adhesion. One representative of 3 to 9 independent experiments is shown. Error bars indicate SEM.