ABSTRACT
This study sought to shed light on the killing effect of peripheral blood mononuclear cells (PBMCs) irradiated by gamma ray at a dose of 1 Gy on cultured human gastric tumor cell line MKN-28. The radiation dose rate of 17 Gy/min was used. The groups in the experiment were MKN-28 cell control group, PBMCs control group, MKN-28 tumor cells with irradiated or non-irradiated PBMCs co-cultured groups. Radiation dosage was one Gray, acridine orange/ethidium bromide (AO/EB) staining was used for observation of the killing effects of PBMCs on tumor cells in different period. Cells were harvested 240 h later and observed by transmission electron microscopy. The result showed the living period of irradiated PBMCs was shorter than that of non-irradiated PBMCs. In the irradiated and non-irradiated groups,a few PBMCs were still alive after being cultured for 240 h, but the cell volume was larger than that of lymphocytes. These cells were identified as monocytes (95%) or DCs (5%) by transmission electron microscopy. The co-culture of irradiated PBMCs and MKN-28 cells showed that tumor cells were eliminated after 96 h. As compared with the non-irradiated goup, the irradiated PBMCs had more potent ability for killing tumor. The results demonstrate that 1 Gy gamma irridiation can improve the killing effect of PBMCs on the tumor cells, and that 1 Gy gamma irritation can also induce shorter living period of lymphocytes in PBMCs cultured in vitro, but such irritation has little effect on the living period of monocytes and DCs in PBMCs.