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Volume 9, Issue 4 (Nov 2021)                   Res Mol Med (RMM) 2021, 9(4): 0-0 | Back to browse issues page

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Faghihi H, Mottaghi Dastgerdi N. A Review on Recommended Mechanisms in Thrombocytopenia and Thrombosis Following ChAdOx1 nCoV-19 Vaccination. Res Mol Med (RMM). 2021; 9 (4)
URL: http://rmm.mazums.ac.ir/article-1-450-en.html
1- Department of Pharmaceutics, School of Pharmacy, Iran University of Medical Sciences, Tehran, Iran (Email: Faghihi.h@iums.ac.ir; Homafaghihipharm@gmail.com; ORCID: 0000-0003-1505-4936) , homafaghihipharm@gmail.com
2- Department of Pharmacognosy and Pharmaceutical Biotechnology, School of Pharmacy, Iran University of Medical Sciences, Tehran, Iran (Email: Mottaghi.n@iums.ac.ir, Mottaghi.negar@gmail.com; ORCID: 0000-0001-8386-774X)
Abstract:   (108 Views)
 Objectives: ChAdOx1 nCov-19 vaccine is a viral vector-based vaccine with desirable protection (about 70.4% two weeks after the second dose). There were few reports on thrombocytopenia associated with thrombotic events shortly after ChAdOx1 nCov-19 vaccination. However, the exact pathophysiologic mechanism of this vaccine-induced thrombotic complication has not been yet elucidated. Vaccine induced thrombotic thrombocytopenia syndrome (VITTS), is associated with the detection of anti-PF4 antibodies, and is not still linked to the previous exposure to heparin.
Methods: In the current review, based on relevantly reported cases, possible mechanisms are suggested which provide a relationship between the results of anti-platelet factor 4 (anti-PF4) antibody assays, previous exposure to heparin, and the involved mechanisms of post-vaccination thrombocytopenia and thrombotic events, which might help the experts for selection of the appropriate therapeutic measures.
Results: Possibly involved mechanisms in VITTS after ChAdOx1 nCoV-19 vaccination include binding of anti-PF4 antibodies to heparin/PF4 complex or to receptor binding domain (RBD) protein/PF4 complex. Additionally, binding of anti-RBD antibodies to RBD protein/PF4 complex could be considered as another mechanism. Finally, anti-RBD or anti-PF4 antibodies may bind to heparin/RBD protein/PF4 complex. Binding of either of the mentioned antibodies to these complexes via the Fc/ Angiotensin-converting enzyme 2 (ACE2) receptors can cause activation/removal of platelets leading to thrombocytopenia and thrombosis.

Conclusion: The suggested mechanisms in this article provide a relationship between the results of anti-PF4 antibody assays, previous exposure to heparin, and the involved mechanisms of post-vaccination thrombocytopenia and thrombotic events, which might help the experts for selection of the therapeutic measures.
 
     
Type of Study: review | Subject: Immunology
Published: 2021/11/3

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