FcRn augments induction of tissue factor activity by IgG-containing immune complexes

Thromboembolism complicates disorders caused by immunoglobulin G (IgG)–containing immune complexes (ICs), but the underlying mechanisms are incompletely understood. Prior evidence indicates that induction of tissue factor (TF) on monocytes, a pivotal step in the initiation, localization, and propaga...

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Veröffentlicht in:Blood 2020-06, Vol.135 (23), p.2085-2093
Hauptverfasser: Cines, Douglas B., Zaitsev, Sergei, Rauova, Lubica, Rux, Ann H., Stepanova, Victoria, Krishnaswamy, Sriram, Sarkar, Amrita, Kowalska, M. Anna, Zhao, Guohua, Mast, Alan E., Blumberg, Laurence J., McCrae, Keith R., Poncz, Mortimer, Hubbard, Jonathan J., Pyzik, Michal, Blumberg, Richard S.
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Sprache:eng
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Zusammenfassung:Thromboembolism complicates disorders caused by immunoglobulin G (IgG)–containing immune complexes (ICs), but the underlying mechanisms are incompletely understood. Prior evidence indicates that induction of tissue factor (TF) on monocytes, a pivotal step in the initiation, localization, and propagation of coagulation by ICs, is mediated through Fcγ receptor IIa (FcγRIIa); however, the involvement of other receptors has not been investigated in detail. The neonatal Fc receptor (FcRn) that mediates IgG and albumin recycling also participates in cellular responses to IgG-containing ICs. Here we asked whether FcRn is also involved in the induction of TF-dependent factor Xa (FXa) activity by IgG-containing ICs by THP-1 monocytic cells and human monocytes. Induction of FXa activity by ICs containing IgG antibodies to platelet factor 4 (PF4) involved in heparin-induced thrombocytopenia (HIT), β-2-glycoprotein-1 implicated in antiphospholipid syndrome, or red blood cells coated with anti-(α)-Rh(D) antibodies that mediate hemolysis in vivo was inhibited by a humanized monoclonal antibody (mAb) that blocks IgG binding to human FcRn. IgG-containing ICs that bind to FcγR and FcRn induced FXa activity, whereas IgG-containing ICs with an Fc engineered to be unable to engage FcRn did not. Infusion of an α-FcRn mAb prevented fibrin deposition after microvascular injury in a murine model of HIT in which human FcγRIIa was expressed as a transgene. These data implicate FcRn in TF-dependent FXa activity induced by soluble and cell-associated IgG-containing ICs. Antibodies to FcRn, now in clinical trials in warm autoimmune hemolytic anemia to lower IgG antibodies and IgG containing ICs may also reduce the risk of venous thromboembolism. •FcRn participates in the induction of TF activity by IgG-containing ICs.•Inhibition of FcRn may reduce the prothrombotic phenotype of patients with disorders mediated by IgG-containing ICs. [Display omitted]
ISSN:0006-4971
1528-0020
DOI:10.1182/blood.2019001133