Some monocytic cytokines are important immune regulators. We have investigated cytokine production by monocytes and the blood levels of IL-1 beta, IL-6, TNF alpha, and TGF beta, in patients with obstructive jaundice. The supernatant from LPS stimulated monocytes from jaundiced patients released significantly increased quantities of TNF alpha by both bioassay and radioimmunoassay (RIA) (12.4 +/- 2.5 fmol/mL and 32.6 +/- 8.3 fmol/mL, respectively, for jaundice, compared with 1.6 +/- 0.3 fmol/mL and 2.4 +/- 0.5 fmol/mL respectively for controls, and also of IL-6 (54.8 +/- 5.0 fmol/mL in jaundice compared with 35.6 +/- 5.0 fmol/mL for controls). The production of IL-1 beta and TGF beta by stimulated monocytes was unchanged. Jaundiced patients had significantly higher plasma TGF beta, but TNF alpha and IL-1 beta were below the limits of detection. The highest monocyte TNF alpha and IL-6 levels were seen in malignant disease patients, especially those with a poor immediate prognosis. We conclude that the production of some cytokines by monocytes is up-regulated in patients with obstructive jaundice.