Original Articles
Vol. 4 No. 3 (2025)
Persistence of functional anti-PF4 antibodies and neutrophil activation in vaccine-induced immune thrombotic thrombocytopenia
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All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
Published: 18 November 2025
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Background: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is characterized by thrombosis in unusual sites triggered by anti-PF4 antibodies. To the best of our knowledge, no studies with very long follow-up on anti-PF4 antibodies persistence have been reported.
Methods: We carried out a multicenter study in 16 VITT patients studied at T0 (acute episode), T1 and T2 (after 6 and 29 months) assessing the persistence of anti-PF4/heparin antibodies and of neutrophil activation.
Results: At T0 80%, at T1 75%, and at T2 11% of VITT patients were positive for anti-PF4/heparin antibodies by ELISA, while 75% at T0, 56% at T1, and 0% at T2 had a positive platelet activation assay. Plasmatic MMP-9 and MMP-9/NGAL were strikingly elevated at diagnosis, but they normalized at T1. No clinical relapses were observed.
Conclusions: Although anti-PF4 antibodies may persist for a long-time following an acute VITT episode, they seem to be clinically irrelevant.
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Citations
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Ethics Approval
the study was approved by the local Ethics Committees (CER Umbria n. 3656/20) and the Bioethics Committee of University of Perugia (n. 222848)How to Cite
1.
Petito E, Mezzasoma AM, Falcinelli E, Conti C, De Candia E, De Cristofaro R, et al. Persistence of functional anti-PF4 antibodies and neutrophil activation in vaccine-induced immune thrombotic thrombocytopenia. Bleeding Thromb Vasc Biol [Internet]. 2025 Nov. 18 [cited 2026 May 25];4(3). Available from: https://www.btvb.org/btvb/article/view/400
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