Hans Zwerger, Produktspezialist at CoaChrom Diagnostica, Vienna, Austria introduced me to an important clinical issue, anti-platelet factor 4 (PF4)/protamine antibodies that are implicated in heparin-induced thrombocytopenia with thrombosis (HIT). As you know, cardiologists employ high doses of standard unfractionated heparin during coronary artery bypass graft surgery, which anesthetists and anesthesiologists measure using the activated clotting time assay or thromboelastography. Near the completion of surgery, the heparin is reversed using protamine sulfate, a DNA-binding protein extracted from salmon sperm. Reversal is also monitored the same way.
Several investigators have demonstrated anti-PF4/protamine antibodies associated with HIT that are detectable by immunoassay in patients who do not appear to have anti-PF4/heparin antibodies, the antibodies usually associated with HIT. One enzyme immunoassay distributor, HYPHEN BioMed claims their assay, ZYMUTEST PF4® detects the anti-PF4/protamine antibody in addition to anti-PF4/heparin antibody, though it does not distinguish the two.
Owing to the potential importance of these findings, I have attached two posters and an article (provided by Mr. Zwerger) describing the incidence and clinical significance of the anti-PF4/protamine antibody as part of the HIT algorithm.