DEVELOPMENT OF ANTIBODIES TO BOVINE AND HUMAN FACTOR-V IN 2 CHILDREN AFTER EXPOSURE TO TOPICAL BOVINE THROMBIN

Purpose: Acquired inhibitors to coagulation factors are rare in pediat ric patients. Exposure to topical bovine thrombin is a risk factor for the development of inhibitors in adult cardiac surgery patients. We r eport two pediatric patients who developed inhibitors to bovine and hu man factor V after exposure to fibrin glue containing bovine thrombin. Patients and Methods: The two patients, ages 3 1/2 years and 10 month s, were studied after cardiac surgery. One patient had clinical bleedi ng. Coagulation factor assays and inhibitor studies were performed. Re sults: The presence of a circulating inhibitor to bovine factor V was observed in both patients and to human factor V in one patient. The in hibition of bovine factor V interfered with standard assays for factor VIII activity using a commercial substrate fortified with bovine fact or V resulting in spurious factor VIII deficiency. In one patient, an inhibitor of bovine thrombin was also identified. The inhibition of hu man factor V activity in one patient may have contributed to clinical bleeding. Conclusions: Pediatric patients exposed to topical bovine th rombin, particularly in the setting of cardiac surgery, are at risk fo r the development of antibodies to bovine thrombin and factor V. This may also result in apparent but spurious depletion of other coagulatio n factors. These antibodies may cross-react with human coagulation fac tors, particularly factor V, resulting in clinical bleeding.