Inactivation of ‘Arvin’ by Plasma Proteins

S ummary The coagulant activity of Arvin is neutralized by incubation with normal human serum. Coagulation experiments, and chromatographic and electrophoretic studies using radioactive Arvin, indicate that Arvin interacts with at least two serum proteins. One of these is α 2 macroglobulin and the other may be antithrombin III. Although these proteins inactivate thrombin also, the mechanisms of neutralization of Arvin and thrombin are not identical. In addition, considerable amounts of radio‐active Arvin are trapped in the fibrin mesh when fibrinogen is clotted with Arvin. Serum samples from patients clinically resistant to Arvin showed complexing of Arvin with a γ globulin fraction, confirming the antibody nature of Arvin resistance.