Abstract Number: PB1903
Meeting: ISTH 2020 Congress
Theme: Thrombotic Microangiopathies » Antiphospholipid Syndrome
Background: Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombotic events and pregnancy complications with persistently positive antiphospholipid antibodies (aPL). Phosphatidylserine-dependent antiprothrombin antibodies (aPS/PT) recognize the phosphatidylserine/prothrombin (PS/PT) complex and are strongly correlated with APS. Recently, the complexes of misfolded proteins with major histocompatibility complex class II (MHC II) molecules are considered as major targets of autoantibodies in autoimmune diseases.
Aims: This study was investigated weather misfolded prothrombin (PT) are transported to the cell surface by MHC II in procoagulant cells, consequently being targeted by aPS/PT.
Methods:
1) The interaction between PT and MHC II alleles was analyzed by flow cytometry (FCM) using the cells co-transfected with PT and different MHC II alleles.
2) Synthesis of PT in monocytes was evaluated in phorbol-12-myristate-13-acetate (PMA) treated THP-1 cells by western blotting and FCM.
3) Cell-surface transport of synthesized PT was investigated by FCM on THP-1 cells treated with PMA and interferon gamma.
4) The presence of cell-surface PT was evaluated on monocyte between APS patients and healthy controls by FCM.
Results:
1) Overexpressed PT/MHC II complexes were detected on THP-1 cell-surface by a mouse monoclonal aPS/PT. We confirmed the dependency of MHC II allele differences on aPS/PT binding.
2) PMA treated THP-1 cells synthesized PT, which showed stronger binding with aPS/PT compared with non-pathogenic monoclonal anti-PT antibody.
3) aPS/PT binding to PT/MHC II complexes was confirmed in co-stimulated THP-1 cells.
4) Cell-surface PT was detected on monocyte in APS patient and aPS/PT binding to the monocyte was confirmed.
Conclusions: We found that PT was synthesized under some conditions and transported to the cell-surface on monocyte in APS. The PT/MHC II complexes on cell-surface of monocytes might be considered as one of the antigenic targets for pathogenic aPS/PT.
To cite this abstract in AMA style:
Fujieda Y, Ohnishi N, Sato T, Kono M, Kato M, Oku K, Amengual O, Arase H, Atsumi T. The Prothrombin/MHC II Complexes on Cell-Surface of Monocytes Is the Antigenic Targets in Antiphospoholipid Syndrome [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/the-prothrombin-mhc-ii-complexes-on-cell-surface-of-monocytes-is-the-antigenic-targets-in-antiphospoholipid-syndrome/. Accessed September 29, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-prothrombin-mhc-ii-complexes-on-cell-surface-of-monocytes-is-the-antigenic-targets-in-antiphospoholipid-syndrome/