Cytokines tumor necrosis factor and interleukin-6 in experimental biliary obstruction in mice.

The putative role of the cytokines interleukin-6 and tumor necrosis factor in the pathophysiology of the complications and mortality after surgery in jaundiced patients was studied in a murine model. Cytokine serum levels were determined in mice with experimental biliary obstruction. As an indicator of the activation status of macrophages, cytokine release by mononuclear phagocytes obtained from such mice was assessed. Following surgery, interleukin-6 levels increased to 2 to 3 ng/ml after 3 to 4 hr, but declined rapidly afterward to levels of 60 pg/ml after 10 days. After 12 days, substantial interleukin-6 levels were observed in jaundiced mice (100 pg/ml), whereas levels in sham mice further decreased (p less than 0.001). The cytokine tumor necrosis factor was frequently present in the serum of jaundiced mice. After 22 days, when killed, all jaundiced mice showed significant tumor necrosis factor levels (p less than 0.001). This was in contrast to sham mice in which tumor necrosis factor was never detected. The presence of an activated state of macrophages in jaundiced mice was concluded from the observed high spontaneous cytokine release and significantly higher release after stimulation (p less than 0.05). The presence of circulating cytokines was discussed in the context of the postoperative complications observed in jaundiced patients.