A Specific Inhibitor of Human Clotting Factor V

Acquired FV inhibitors: a needless iatrogenic complication of bovine thrombin exposure

“…Many of the early reported cases of FV inhibitors developed spontaneously in patients without any clearly identifiable cause. Common clinical events that preceded inhibitor development in these patients included surgical procedures, infections, or exposure to antibiotics (in particular, aminoglycosides) or blood transfusions 4‐23 . Other conditions associated with inhibitors included pre‐existing autoimmune diseases, malignancies, and pregnancy 14,18,19,24‐41 .…”

“…The mainstay of therapy is immunosuppression. Corticosteroids (prednisone, dexamethasone) and related compounds (adrenocorticotropic hormone), 5,6,8,12,14‐17,26,74,78,79,83‐91 as well as cyclosporine A and cytotoxic chemotherapy agents, have demonstrated activity 12,16,18,27,28,31,33,47,77‐85,87,89,90,92 . IVIG has also been quite effective 22,33,47,49,54,56,60,64,65,80,87 .…”

Acquired Inhibitors in Nonhemophilic Patients

“…Inhibitors which Inactivate Factor V Eight cases with antifactor V inhibitors have been reported in the litera ture [16,45,47,70,102,120,123], all of them referring to patients with previously normal coagulation. The action of the inhibitor is specifically directed against factor V. A comparison with factor VIII inhibitors reveals a number of interesting differences and similarities.…”

“…In three cases, the factor V inhibitor developed shortly after blood transfusions [45,70], in two cases a history of penicillin hypersensitivity was reported [102,123] and in one case [120] the inhibitor was thought to be due to cephalothin therapy.…”