High Molecular Weight Kininogen Inhibits Fibrinogen Binding to Cytoadhesins of Neutrophils and Platelets
Fibrinogen inhibited 125I-high molecular weight kininogen (HMWK) binding and displaced bound 125I-HMWK from neutrophils. Studies were performed to determine whether fibrinogen could bind to human neutrophils and to describe the HMWK-fibrinogen interaction on cellular surfaces. At 4°C, the binding of...
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Veröffentlicht in: | The Journal of cell biology 1989-07, Vol.109 (1), p.377-387 |
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Sprache: | eng |
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Zusammenfassung: | Fibrinogen inhibited 125I-high molecular weight kininogen (HMWK) binding and displaced bound 125I-HMWK from neutrophils. Studies were performed to determine whether fibrinogen could bind to human neutrophils and to describe the HMWK-fibrinogen interaction on cellular surfaces. At 4°C, the binding of 125I-fibrinogen to neutrophils reached a plateau by 30 min and did not decrease. At 23 and 37°C, the amount of 125I-fibrinogen bound peaked by 4 min and then decreased over time because of proteolysis of fibrinogen by human neutrophil elastase (HNE). Zn++ (50 μM) was required for binding of 125I-fibrinogen to neutrophils at 4°C and the addition of Ca++ (2 mM) increased the binding twofold. Excess unlabeled fibrinogen or HMWK completely inhibited binding of 125I-fibrinogen. Fibronectin degradation products (FNDP) partially inhibited binding, but prekallikrein and factor XII did not. The binding of 125I-fibrinogen at 4°C was reversible with a 50-fold molar excess of fibrinogen or HMWK. Binding of 125I-fibrinogen, at a concentration range of 5-200 μg/ml of added radioligand, was saturable with an apparent Kd of 0.17 μM and 140,000 sites/cell. The binding of 125I-fibrinogen to neutrophils was not inhibited by the peptide RGDS derived from the α chain of fibrinogen or by the mAb 10E5 to the platelet glycoprotein IIb/IIIa heterodimer. Fibrinogen binding was inhibited by a γ-chain peptide CYGHHLGGAKQAGDV and by mAb OKM1 but was not inhibited by OKM10, an mAb to a different domain of the adhesion glycoprotein Mac-1 (complement receptor type 3 [CR3]). HMWK binding to neutrophils was not inhibited by OKM1. These observations were consistent with a further finding that fibrinogen is a noncompetitive inhibitor of 125I-HMWK binding to neutrophils. Fibrinogen binding to ADP-stimulated platelets was increased twofold by Zn++ (50 μM) and was inhibited by HMWK. These studies indicate that fibrinogen specifically binds to the C3R receptor on the neutrophil surface through the carboxy terminal of the γ-chain and that HMWK interferes with the binding of fibrinogen to integrins on both neutrophils and activated platelets. |
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ISSN: | 0021-9525 1540-8140 |
DOI: | 10.1083/jcb.109.1.377 |