REDUCING ENVIRONMENT PROTECTS SINUSOIDAL LYMPHOCYTES ISOLATED FROM NORMAL HUMAN LIVER FROM APOPTOSIS

Background/Aims: We previously reported that the populations of lympho cytes and the expression of activated antigens in human sinusoidal mon onuclear cells were different from those in peripheral blood mononucle ar cells. Attempts to culture these cells for further study failed bec ause they died rapidly under standard culture conditions in vitro afte r isolation from the liver. In this study, we evaluated the characteri stics of cell death and the effects of various culture conditions on t he viability of these cells. Methods: Sinusoidal mononuclear cells wer e isolated from University of Wisconsin solution that had been perfuse d through the portal veins of normal healthy human livers harvested fo r transplantation into living related recipients. Results: 70% of sinu soidal mononuclear cells cultured in vitro were nonviable within 48 h after isolation, while only 10% of peripheral blood mononuclear cells died under the same conditions. Sinusoidal mononuclear cells showed DN A ladder formation of DNA on electrophoresis and characteristic morpho logical pattern on electron microscopic examination that suggested the y had died in an apoptotic manner. The addition of human liver extract s or 2-mercaptoethanol and reduced glutathione to the cultures rescued the sinusoidal mononuclear cells from apoptosis. Furthermore, diamide , a sulfhydryl group specific oxidant, negated the effect of the liver extract. Conclusion: In comparison with peripheral blood mononuclear cells, human sinusoidal mononuclear cells were more subject to death b y apoptosis ex vivo, which was reversed by exogenous agents producing reducing conditions. These results suggested that hepatic sinusoidal m ononuclear cells might express a different sensitivity to redox enviro nment than peripheral blood mononuclear cells.