Impact of N-glycan mediated shielding of ADAMTS-13 on the binding of pathogenic antibodies in immune thrombotic thrombocytopenic purpura

J Thromb Haemost. 2023 Dec;21(12):3402-3413. doi: 10.1016/j.jtha.2023.08.017. Epub 2023 Aug 25.


Background: Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic disorder, with 1.5 to 6.0 cases per million per year. The majority of patients with TTP develop inhibitory autoantibodies that predominantly target the spacer domain of ADAMTS-13. ADAMTS-13 is responsible for cleaving von Willebrand factor (VWF) multimers, thereby regulating platelet adhesion at sites of high-vascular shear stress. Inhibition and/or clearance of ADAMTS-13 by pathogenic autoantibodies results in accumulation of VWF multimers that promotes the formation of platelet-rich microthrombi. Previously, we have shown that insertion of a single N-glycan (NGLY) in the spacer domain prevents the binding of antispacer domain antibodies.

Objectives: To explore whether NGLY mediated shielding of the ADAMTS-13 spacer domain effectively prevents binding of pathogenic antispacer autoantibodies in patients with immune-mediated TTP (iTTP).

Methods: We screened 5 NGLY-ADAMTS-13 variants (NGLY3, NGLY7, NGLY8, NGLY3+7, and NGLY3+8) for binding of autoantibodies and for their activity in the presence and absence of 50 samples derived from patients with iTTP.

Results: NGLY variants showed greatly reduced antibody binding, down to 27% of wild-type (wt) ADAMTS-13 binding. Moreover, NGLY variants of ADAMTS-13 remained more active in FRETS-VWF73 assay in the presence of the plasma samples from these 50 patients with acute phase iTTP when compared with wtADAMTS-13. On average, wtADAMTS-13 activity was reduced to 37% of regular levels in the presence of plasma, while NGLY3 and NGLY3+7 remained 69% and 81% active, respectively.

Conclusion: These results reinforce our previous findings that NGLYs shield ADAMTS-13 from antibody binding and hence restore ADAMTS-13 activity in the presence of autoantibodies.

Keywords: ADAMTS-13; autoantibodies; hemostasis; thrombotic microangiopathies; thrombotic thrombocytopenic purpura.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAMTS13 Protein
  • Autoantibodies
  • Blood Platelets / metabolism
  • Humans
  • Purpura, Thrombocytopenic, Idiopathic*
  • Purpura, Thrombotic Thrombocytopenic*
  • Thrombosis*
  • von Willebrand Factor / metabolism


  • ADAMTS13 Protein
  • von Willebrand Factor
  • Autoantibodies