Variable serotonin release assay pattern and specificity of PF4‐specific antibodies in HIT, and clinical relevance

• Published in: Journal of thrombosis and haemostasis 2022-11, Vol.20 (11), p.2646-2655
• Main Authors: Rollin, Jérôme, Charuel, Noémie, Gruel, Yves, Billy, Sandra, Guéry, Eve‐Anne, May, Marc‐Antoine, Pouplard, Claire, Vayne, Caroline
• Format: Article
• Language: English
• Subjects: Antibodies; antibody; Anticoagulants - adverse effects; Heparin; Heparin - adverse effects; Humans; Immunoglobulin G; Immunologic Factors - adverse effects; Optical density; Original; Patients; Platelet Factor 4; PLATELETS; Serotonin; serotonin release assay; Thrombocytopenia; Thrombocytopenia - chemically induced; Thrombocytopenia - diagnosis; Thrombosis; Thrombosis - chemically induced; Thrombosis - complications; Thrombosis - diagnosis
• ISSN: 1538-7933; 1538-7836; 1538-7836
• DOI: 10.1111/jth.15848

Background The diagnosis of heparin‐induced thrombocytopenia (HIT) requires functional assays to demonstrate that platelet factor 4 (PF4)‐specific antibodies activate platelets, typically when therapeutic heparin (H) concentrations are tested (“classical” pattern). Some HIT samples also activate platelets without heparin (“atypical” pattern), but with unclear clinical significance. Objectives We aimed to assess whether platelet activation pattern and some characteristics of PF4‐specific antibodies were associated with the severity of HIT. Patients/Methods Serotonin release assay (SRA) pattern of 81 HIT patients were analyzed and compared with their clinical and biological data, including levels of anti‐PF4/H immunoglobulin G (IgG) and anti‐PF4 IgG in 47 of them. Results Higher anti‐PF4/H IgG titers were measured in patients with an “atypical” SRA (optical density 2.52 vs. 1.94 in those with a “classical” pattern, p