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Isolation of Labile Multi-protein Complexes by in vivo Controlled Cellular Cross-Linking and Immuno-magnetic Affinity Chromatography
Published on: March 9, 2010
Integrin-associated protein is an adhesion receptor on sickle red blood cells for immobilized thrombospondin
J E Brittain1, K J Mlinar, C S Anderson
1Department of Pharmacology, School of Medicine, The University of North Carolina at Chapel Hill 27599, USA.
The adhesive protein thrombospondin (TSP) potentially mediates sickle (SS) red blood cell (RBC) adhesion to the blood vessel wall, thereby contributing to vaso-occlusive crises in sickle cell disease. We previously reported that SS RBCs bind to immobilized TSP under flow conditions, whereas normal (AA) red cells do not. However, the SS RBC receptors that mediate this interaction are largely unknown. Here it is reported that integrin-associated protein (IAP), or CD47, mediates the adhesion of these cells to immobilized TSP under both flow and static conditions. A peptide derived from the C-terminal IAP binding site of TSP also supports sickle cell adhesion; adhesion to this peptide or to TSP is inhibited specifically by the anti-IAP monoclonal antibody, 1F7. Furthermore, these data suggest that IAP on SS RBCs is structurally different from that expressed on AA RBCs but that IAP expression levels do not vary between AA and SS RBCs. This structural difference may contribute to the enhanced adhesion of SS RBCs to immobilized TSP. These results identify IAP as a TSP receptor on SS RBCs and suggest that this receptor and its binding site within TSP represent potential therapeutic targets to decrease vaso-occlusion. (Blood. 2001;97:2159-2164)
The adhesive protein thrombospondin (TSP) potentially mediates sickle (SS) red blood cell (RBC) adhesion to the blood vessel wall, thereby contributing to vaso-occlusive crises in sickle cell disease. We previously reported that SS RBCs bind to immobilized TSP under flow conditions, whereas normal (AA) red cells do not. However, the SS RBC receptors that mediate this interaction are largely unknown. Here it is reported that integrin-associated protein (IAP), or CD47, mediates the adhesion of these cells to immobilized TSP under both flow and static conditions. A peptide derived from the C-terminal IAP binding site of TSP also supports sickle cell adhesion; adhesion to this peptide or to TSP is inhibited specifically by the anti-IAP monoclonal antibody, 1F7. Furthermore, these data suggest that IAP on SS RBCs is structurally different from that expressed on AA RBCs but that IAP expression levels do not vary between AA and SS RBCs. This structural difference may contribute to the enhanced adhesion of SS RBCs to immobilized TSP. These results identify IAP as a TSP receptor on SS RBCs and suggest that this receptor and its binding site within TSP represent potential therapeutic targets to decrease vaso-occlusion. (Blood. 2001;97:2159-2164)
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