KUPFFER CELL-MEDIATED CYTOTOXICITY AGAINST HEPATOMA-CELLS OCCURS THROUGH PRODUCTION OF NITRIC-OXIDE AND ADHESION VIA ICAM-1 CD18/

Rat Kupffer cell (KC)-mediated cytotoxicity against both the syngeneic hepatoma cell line AH70 and hepatocytes was evaluated by changes in m itochondrial function, and the possible role of ICAM-1/CD18 in the int eraction between the cells was studied. Rhodamine 123 fluorescence, a marker of the mitochondrial membrane potential, decreased in AH70 cell s after co-culture with KC, while that in hepatocytes was unchanged by co-culture. This decrease was blocked by anti-ICAM-1, anti-CD18 and t he inhibition of nitric oxide synthesis. Cytometric studies demonstrat ed that ICAM-1 expression on AH70 cells increased after addition of IF N-gamma, IL-1 beta, tumor necrosis factor (TNF)-alpha or KC, while in hepatocytes ICAM-1 was not increased. Anti-ICAM-1 pretreatment inhibit ed the increase in ICAM-1 expression and the decrease in rhodamine 123 fluorescence on AH70 cells after co-culture with KC. CD18 on KC was i ncreased only after co-culture with AH70. TNF-alpha but not IFN-gamma was detected in the supernatant of co-culture between KC and AH70 cell s, and this production was partially inhibited by anti-ICAM-1 and anti -CD18. The activity of inducible nitric oxide synthase in Kupffer cell s and the levels of nitrites and nitrates in the co-culture supernatan t increased over time, and this increase was attenuated either by addi tion of NO synthesis inhibitors, anti-ICAM-1 or anti-CD18. These resul ts indicate that the rat KC causes mitochondrial dysfunction in cancer cells via the production of NO and cell-to-cell adhesion via ICAM-1/C D18 has an important role in this cytotoxic process.