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 degrees C, the binding of 125I-fibrinogen to neutrophils reached a plateau by 30 min and did not decrease. At 23 and 37 degrees 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 microM) was required for binding of 125I-fibrinogen to neutrophils at 4 degrees 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 degrees C was reversible with a 50-fold molar excess of fibrinogen or HMWK. Binding of 125I-fibrinogen, at a concentration range of 5-200 micrograms/ml of added radioligand, was saturable with an apparent Kd of 0.17 microM and 140,000 sites/cell. The binding of 125I-fibrinogen to neutrophils was not inhibited by the peptide RGDS derived from the alpha chain of fibrinogen or by the mAb 10E5 to the platelet glycoprotein IIb/IIIa heterodimer. Fibrinogen binding was inhibited by a gamma-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 microM) 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 gamma-chain and that HMWK interferes with the binding of fibrinogen to integrins on both neutrophils and activated platelets.
Gustafson
E J
EJ
Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Lukasiewicz
H
H
Wachtfogel
Y T
YT
Norton
K J
KJ
Schmaier
A H
AH
Niewiarowski
S
S
Colman
R W
RW
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000378:metabolism*; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D002413:Cations, Divalent; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules; D002462:Cell Membrane / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D007704:Kininogens / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D011485:Protein Binding; D011951:Receptors, Complement / Q000378:metabolism; D017463:Receptors, Complement 3b
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D002413:Cations, Divalent; D015815:Cell Adhesion Molecules; D007704:Kininogens; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D005340:Fibrinogen