Antigenic similarities between human plasma inhibitor of thrombin (At-III) and its analogues from other mammals.

Cross reactions investigated by double immunodiffusion and by immunoelectrophoresis between human plasma and plasma of 5 animal species using a specific rabbit antiserum against human At-III revealed antigenic relationships between the antithrombins of these species. But the quantitative measurements of At-III by immunologic methods (electro-immunodiffusion and radial immunodiffusion), using the rabbit antiserum, were not possible in common laboratory animals, except in baboons.