Tumor immunoglobulin with antibody activity against blood coagulation factors

A cultured tumor cell line from the Greene lymphoma was shown in vitro to secrete immunoglobins of the IgG2 subclass (TcIg), which possessed a direct inhibiting effect on blood coagulation. TcIg prolonged the thrombin time (TT) of normal hamster plasma in vitro. Moreover, the effect of heparin which prolonged the plasma thrombin time was reinforced when TcIg was added to the test. This property was not neutralized by protamine sulfate. In the plasma kaolin clotting time test (KCT), the addition of TcIg lead to an anticoagulant effect, but weaker than in TT. The mixing pattern of normal plasma with tumor-bearing hamster plasma did not reveal the presence of circulating inhibitor in tumor plasma. It was suggested that TcIg had heparin-like activity.