The blood level of tumor necrosis factor (TNF) was determined in 20 normal individuals, 52 patients with disseminated intravascular coagulation (DIC), 22 pre-DIC patients, and 39 non-DIC patients and 10 thrombotic thrombocytopenic purpura (TTP) patients. TNF was not detected in the normal subjects and the level was very low in non-DIC patients. However, the level was significantly elevated in DIC patients. TNF was also increased significantly in pre-DIC patients shortly before the onset of DIC as compared with non-DIC patients. This increase in circulating TNF may be associated with DIC. In TTP, the blood level of TNF was increased at onset but decreased at remission. According to underlying diseases, TNF was higher in DIC associated with solid cancer than in DIC associated with leukemia or sepsis. In solid cancer, a large amount of tissue factor may be produced as the immune system is activated, cytokines such as TNF are released into the circulation, and endothelial cells and monocytes are activated. The blood TNF level was not significantly different between DIC patients with organ failure and DIC those without organ failure. From these findings, the increase in circulating TNF is considered to be a direct pathogenic factor in DIC or TTP rather than a consequence of organ failure due to DIC.
