Production of anti-PF4 antibodies in antiphospholipid antibody-positive patients is not affected by COVID-19 vaccination. Issue 1 (7th February 2022)

• Record Type: Journal Article
• Authors: Lonati, Paola Adele; Bodio, Caterina; Scavone, Mariangela; Martini, Giuliana; Pesce, Elisa; Bandera, Alessandra; Lombardi, Andrea; Gerosa, Maria; Franceschini, Franco; Tincani, Angela; Podda, Gianmarco; Abrignani, Sergio; Grifantini, Renata; Cattaneo, Marco; Borghi, Maria Orietta; Meroni, Pier Luigi
• Is Part Of: RMD open. Volume 8:Issue 1(2022)
• Publication Date: 2022-02-07
• Subjects: antibodies -- antiphospholipid -- COVID-19 -- vaccination; Musculoskeletal system -- Diseases -- Periodicals; Rheumatism -- Periodicals; 616.7005
• DOI: 10.1136/rmdopen-2021-001902
• Languages: English
• ISSNs: 2056-5933

Abstract

Abstract : Background: Antibodies against cationic platelet chemokine, platelet factor 4 (PF4/CXCL4), have been described in heparin-induced thrombocytopenia (HIT), but also in patients positive for antiphospholipid antibodies (aPL) even in the absence of heparin treatment and HIT-related clinical manifestations. Anti-PF4 antibodies have been recently described also in subjects who developed thrombosis with thrombocytopenia syndrome (TTS) in association with adenoviral vector-based, but not with mRNA-based, COVID-19 vaccines. Objective: To investigate whether COVID-19 vaccination affects the production of anti-PF4 antibodies in aPL-positive patients and in control groups. Methods: Anti-PF4 immunoglobulins were detected in patients' and controls' serum samples by ELISA and their ability to activate normal platelets was assessed by the platelet aggregation test. Results: Anti-PF4 were found in 9 of 126 aPL-positive patients, 4 of 50 patients with COVID-19, 9 of 49 with other infections, and 1 of 50 aPL-negative patients with systemic lupus erythematosus. Clinical manifestations of TTS were not observed in any aPL patient positive for anti-PF4, whose serum failed to cause platelet aggregation. The administration of COVID-19 vaccines did not affect the production of anti-PF4 immunoglobulins or their ability to cause platelet aggregation in 44 aPL-positive patients tested before and after vaccination. Conclusions: Heparin treatment-independent anti-PF4 antibodies can be found in aPL-positive patients and asymptomatic carriers, but their presence, titre as well as in vitro effect on platelet activation are not affected by COVID-19 vaccination.