Cross-Reactivity of Rabbit Anti-Bovine Thrombin IgGs with Human α-Thrombin and a Recombinant Version of Human Thrombin (Recothrom™).

Abstract 4211

It has been reported that patients exposed to topical bovine thrombin preparations may develop antibodies to bovine thrombin, factor V or various other proteins. In some cases these antibodies can cross-react with the corresponding human coagulation proteins. The present study was undertaken to determine if the antibodies induced by bovine thrombin antigens in rabbits could also cross-react with human a-thrombin and Recothrom^TM. Bovine crude thrombin and its purified versions, thrombin 4A and 4B, were administered to individual groups of rabbits on 0, 21, 42, 91, 123 and 151 days. Blood was drawn from each rabbit on days 30, 50, 105, 137 and 165, respectively. The antiserum from each rabbit and the pooled antisera from individual groups were purified to obtain the IgGs. Utilizing western blotting method, the possible cross-reactivity of each IgG with human thrombin and Recothrom^TM was explored using serial diluted human α-thrombin (20μg, 10μg, and 5μg) and Recothrom^TM (10U, 5U, and 2.5U). No cross-reactivity with either human α-thrombin or Recothrom^TM was observed with both anti-bovine crude thrombin IgGs and thrombin 4B IgGs collected on day 30 and day 165. However, anti-bovine thrombin 4A IgGs showed cross-reactivity with both human α-thrombin and Recothrom^TM. Cross-reactivity of anti-bovine thrombin 4A IgGs with human α-thrombin and Recothrom^TM was augmented with time. The minimum concentration of 4A IgG required to exhibit cross-reactivity with human α-thrombin and Recothrom^TM varied considerably among individual rabbits. These results demonstrate that rabbit anti-bovine thrombin 4A IgG could cross-react with both human a-thrombin and Recothrom^TM in a time/concentration-dependent manner.