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

An atypical SRA pattern with elevated anti-PF4/H IgG titers seems associated with an increased risk of thrombosis in HIT. IgG antibodies to native PF4 may contribute to more severe and persistent thrombocytopenia, and their detection could be useful in clinical practice.