Increased tissue factor activity generation in vitro by canine blood leukocytes associated with allogeneic kidney transplantation and rejection.

Using a canine model, leukocyte populations enriched for monocytes and lymphocytes were isolated from blood during three week periods after kidney allotransplantation corresponding to episodes of acute rejection. Relative to controls, these cells incubated in vitro for five hours were found to generate increased amounts of PCA (procoagulant activity) characterized as tissue factor, the extrinsic clotting pathway activator. Controls included comparable blood leukocyte populations isolated from kidney autograft recipients and healthy animals. Differences in results for these two control groups were insignificant. These contrasts observed between allografted animals and controls demonstrate that leukocyte PCA generation is stimulated by the allogeneicity of histoincompatible kidneys rather than by direct effects of organ transplantation or non-specific postoperative effects. Results of in vitro transfer experiments provide evidence that cellular stimulation or induction in vivo accounted for the PCA increases observed. Stimulation of leukocyte tissue factor generation as a consequence of allogeneic kidney transplantation may in part account for coagulopathies and fibrin deposition during kidney rejection.