To investigate the effect of killer cell immunoglobulin-like receptor (KIR) gene in immune killing of hepatoma cells.

Peripheral blood mononuclear cell (PBMC) and hepatoma cells were co-cultured with different effector-target ratios. The expression of KIR gene family in PBMC, the content to interferon-γ (IFN-γ), the morphological change of hepatoma cell and the cytotoxicity to hepatoma cell by PBMC were observed after the co-incubation with different effector-target ratios. The comparison on cytotoxicity rates was conducted using one-way analysis of variance and LSD-t test.

The expression of activating KIR gene increased after 12 h of co-culture, but decreased after 24 h of co-culture. The expression of inhibitory KIR gene decreased after 12 h of co-culture. DAP12 maintained high expression all the time. The content of IFN-γ in PBMC decreased with the increase of effector-target ratio and reached the peak at 12 h of co-culture. Hepatoma cells co-cultured with different effector-target ratios were observed with increased chromatin condensation, rising proportion of cells with hemispherical or half moon shape and marginalized nucleus, and stagnant of active cell division. The cytotoxicity rate of effector-target ratio 1∶1, 10∶1 and 50∶1 was (8±3) %, (14±4) % and (32±6) %, respectively, with 50∶1 group significantly higher than 11∶1 and 10∶1 group (LSD-t=5.97, 4.61; P<0.05).

The activating KIR gene plays an important role in immune killing of hepatoma cells.