Fibrinogen Promotes Neutrophil Activation and Delays Apoptosis

The acute phase of the inflammatory response involves an increase in the concentrations of different plasma proteins that include fibrinogen (Fbg) and multiple proinflammatory mediators. In parallel, neutrophil activation is thought to play a crucial role in several inflammatory conditions, and it h...

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Published in:The Journal of immunology (1950) 2001-02, Vol.166 (3), p.2002-2010
Main Authors: Rubel, Carolina, Fernandez, Gabriela C, Dran, Graciela, Bompadre, Macarena Beigier, Isturiz, Martin A, Palermo, Marina S
Format: Article
Language:English
Subjects:
Adjuvants, Immunologic - physiology
Antigens, CD - biosynthesis
Antigens, Differentiation - biosynthesis
Apoptosis - immunology
Calcium - metabolism
CD11b antigen
Cell Adhesion Molecules
Cell Degranulation - immunology
Cell Membrane - immunology
Cell Membrane - metabolism
Cell Separation
Fibrinogen - physiology
Humans
Macrophage-1 Antigen - biosynthesis
Neutrophil Activation
Neutrophils - cytology
Neutrophils - immunology
Neutrophils - metabolism
Receptors, IgG - biosynthesis
Solubility
Up-Regulation - immunology
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Summary:The acute phase of the inflammatory response involves an increase in the concentrations of different plasma proteins that include fibrinogen (Fbg) and multiple proinflammatory mediators. In parallel, neutrophil activation is thought to play a crucial role in several inflammatory conditions, and it has been recently demonstrated that Fbg specifically binds to the alpha-subunit of CD11b/CD18 on neutrophil surface. Although several reports have shown that CD11b engagement modulates neutrophil responses, the effect of human Fbg (hFbg), one of CD11b physiologic ligands, has not been exhaustively investigated. We have now shown that incubation of purified neutrophils with hFbg induces a transient and rapid elevation of free intracellular Ca2+. This early intracellular signal is accompanied by changes in the expression of neutrophil activation markers, including enhancement of CD11b and CD66b, and down-regulation of FcgammaRIII. In addition, we have evaluated the effect of hFbg on two functional events related to expression and resolution of inflammation: cytotoxic capacity and rate of neutrophil apoptosis. We have found that activation of neutrophils by hFbg resulted in both enhancement of phagocytosis and Ab-dependent cellular cytotoxicity, and delay of apoptosis. We conclude that during inflammatory processes, soluble Fbg could influence neutrophil responses, increasing and prolonging their functional capacity.
ISSN:0022-1767
1550-6606
DOI:10.4049/jimmunol.166.3.2002