Heparin-induced thrombocytopenia and thrombosis

Thrombocytopenia and thrombosis, recognized complications of heparin therapy, have long been thought to be antibody mediated. However, in vitro studies have failed to provide satisfactory explanations for platelet destruction and paradoxical thrombosis in patients with heparin sensitivity. Recently, several groups of investigators have shown that plasma from patients with heparin-induced thrombocytopenia and thrombosis contains IgG and IgM antibodies specific for complexes containing heparin and platelet factor 4, a heparin-binding protein normally contained in platelet alpha granules. These observations have provided new insights into the pathogenesis of this serious side-effect of heparin therapy and should point the way to improved diagnosis, prevention, and, possibly, treatment.