Heparin-induced thrombocytopenia type II (HIT II) is usually mediated by immunoglobulin G (IgG) antibodies that lead to platelet activation via the FcγIIA-receptor. Here we describe a patient who developed HIT II after aortocoronary bypass surgery. His serum contained an antibody that was detectable by the heparin-induced platelet activation assay (HIPA) and by the ID-HPF4 particle agglutination assay. The flow cytometric analysis showed that the antibody was of the IgA class.
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