RT Journal Article
SR Electronic
T1 Production of anti-PF4 antibodies in antiphospholipid antibody-positive patients is not affected by COVID-19 vaccination
JF RMD Open
JO RMD Open
FD EULAR
SP e001902
DO 10.1136/rmdopen-2021-001902
VO 8
IS 1
A1 Paola Adele Lonati
A1 Caterina Bodio
A1 Mariangela Scavone
A1 Giuliana Martini
A1 Elisa Pesce
A1 Alessandra Bandera
A1 Andrea Lombardi
A1 Maria Gerosa
A1 Franco Franceschini
A1 Angela Tincani
A1 Gianmarco Podda
A1 Sergio Abrignani
A1 Renata Grifantini
A1 Marco Cattaneo
A1 Maria Orietta Borghi
A1 Pier Luigi Meroni
YR 2022
UL http://rmdopen.bmj.com/content/8/1/e001902.abstract
AB 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.