Tissue factor activity of rabbit peritoneal macrophages: influence of immune stimulation

Rabbit peritoneal macrophages exhibit a potent tissue factor activity able to trigger the extrinsic pathway of blood coagulation. This activity is elicited by the inflammatory reaction. Local injection of antigen in immunized animals leads to a lowering of the macrophage procoagulant activity. The mechanism of this phenomenon was investigated in cell culture. After a 24 hour culture, sticking macrophages as well as the culture supernatant exhibit a potent tissue factor activity, both closely related to the initial cell concentration. When the cells are collected from immunized rabbits the presence of the antigen in culture medium is able to significantly enhance the procoagulant activity of the supernatant. These data allow to propose a mechanism for the "macrophage disappearance reaction" and some related phenomena.