Red blood cell microvesicles activate the contact system, leading to factor IX activation via 2 independent pathways.

Published

Journal Article

Storage lesion-induced, red cell-derived microvesicles (RBC-MVs) propagate coagulation by supporting the assembly of the prothrombinase complex. It has also been reported that RBC-MVs initiate coagulation via the intrinsic pathway. To elucidate the mechanism(s) of RBC-MV-induced coagulation activation, the ability of storage lesion-induced RBC-MVs to activate each zymogen of the intrinsic pathway was assessed in a buffer system. Simultaneously, the thrombin generation (TG) assay was used to assess their ability to initiate coagulation in plasma. RBC-MVs directly activated factor XII (FXII) or prekallikrein, but not FXI or FIX. RBC-MVs initiated TG in normal pooled plasma and in FXII- or FXI-deficient plasma, but not in FIX-deficient plasma, suggesting an alternate pathway that bypasses both FXII and FXI. Interestingly, RBC-MVs generated FIXa in a prekallikrein-dependent manner. Similarly, purified kallikrein activated FIX in buffer and initiated TG in normal pooled plasma, as well as FXII- or FXI-deficient plasma, but not FIX-deficient plasma. Dual inhibition of FXIIa by corn trypsin inhibitor and kallikrein by soybean trypsin inhibitor was necessary for abolishing RBC-MV-induced TG in normal pooled plasma, whereas kallikrein inhibition alone was sufficient to abolish TG in FXII- or FXI-deficient plasma. Heating RBC-MVs at 60°C for 15 minutes or pretreatment with trypsin abolished TG, suggesting the presence of MV-associated proteins that are essential for contact activation. In summary, RBC-MVs activate both FXII and prekallikrein, leading to FIX activation by 2 independent pathways: the classic FXIIa-FXI-FIX pathway and direct kallikrein activation of FIX. These data suggest novel mechanisms by which RBC transfusion mediates inflammatory and/or thrombotic outcomes.

Full Text

Duke Authors

Cited Authors

  • Noubouossie, DF; Henderson, MW; Mooberry, M; Ilich, A; Ellsworth, P; Piegore, M; Skinner, SC; Pawlinski, R; Welsby, I; Renné, T; Hoffman, M; Monroe, DM; Key, NS

Published Date

  • March 5, 2020

Published In

Volume / Issue

  • 135 / 10

Start / End Page

  • 755 - 765

PubMed ID

  • 31971571

Pubmed Central ID

  • 31971571

Electronic International Standard Serial Number (EISSN)

  • 1528-0020

Digital Object Identifier (DOI)

  • 10.1182/blood.2019001643

Language

  • eng

Conference Location

  • United States