Plasma inhibitory activity against tumour necrosis factor in fulminant hepatic failure.

1. Soluble tumour necrosis factor receptors released into the circulation inhibit the effects of excess tumour necrosis factor-alpha and represent an important protective response. 2. In this study we have measured the levels of tumour necrosis factor and soluble tumour necrosis factor receptors p55 and p75 in the plasma of 10 patients with fulminant hepatic failure and 10 healthy control subjects. The capacity of the plasmas at varying dilutions to inhibit the biological activity of 1000 pg/ml of recombinant tumour necrosis factor in a tumour necrosis factor cytotoxicity assay in vitro was also determined. 3. The mean plasma levels of tumour necrosis factor in patients with fulminant hepatic failure (48.4 +/- 10.9 pg/ml) were significantly increased compared with normal control subjects (6.1 +/- 1.04 pg/ml, P < 0.01). Plasma soluble tumour necrosis factor receptors p55 and p75 were also significantly elevated in patients with fulminant hepatic failure (18.16 +/- 9.94 ng/ml and 16.06 +/- 9.93 ng/ml respectively) when compared with normal control subjects (1.28 +/- 0.24 ng/ml and 1.62 +/- 0.91 ng/ml, P < 0.001). 4. Fulminant hepatic failure plasma had a much lower capacity to inhibit tumour necrosis factor bioactivity in vitro, with a statistically significant difference between the inhibitory capacity of the fulminant hepatic failure and normal plasma seen at plasma dilutions of 1:5 and 1:20 (P < 0.05). 5. The reduced tumour necrosis factor neutralization capacity observed in fulminant hepatic failure, despite the increased levels of soluble tumour necrosis factor receptors, suggests enhanced susceptibility to the potential deleterious effects of tumour necrosis factor in fulminant hepatic failure.