The specific and non-specific cytotoxic activity of killer cells against gastric cancer cells induced by cytokines

Abstract

Objective To observe the roles of specific and non-specific cytotoxic activity in cyto-kine-induced killer cells (CIK) against gastric cancer (SGC-7901 ) cells in vitro. Methods Dendritic cells (DC) and CIK were induced from peripheral blood mononuclear cells (PBMC) from healthy donors. The DC were sensitized with tumor antigen extracted from gastric cancer SGC-7901 cells. The CIK were in-duced with DC to form DC-CIK,or induced with gastric cancer antigen-pulsed DC to form antigen-DC-CIK. On the 14th day of culture,CIK, DC-CIK and antigen-DC-CIK phenotypes (CD3 ,CD3/CD8 and CD3/CD56) ware analyzed by flow cytometry. CIK, DC-CIK and antigen-DC-CIK were used as the effector cells, and the SGC-7901 cells with or without blockade of major histocompatibility complex (MHC) molecule as the target cells. At 5: 1,10:1 and 20:1 effector-target ratio,the cytotoxic activity was detected by MTT. Results On the 14th day of culture,the proportion of CD3~+ CD8~+ and CD3~+ CD56~+ double positive cells in antigen-DC-CIK was significantly higher than that in DC-CIK and pure CIK (P <0.01 ). At 20:1 effector-target ratio in vitro,the cytotoxic activity of CIK, DC-CIK and antigen-DC-CIK against SGC-7901 cells was (46.6± 2.2) %, (52.6 ± 1.6) % and (72.5±2.1 ) % (P < 0.01 ), and after MHC molecule was blocked in SGC-7901 cells, the cytotoxic activity was (44.3 ± 1.1 ) %, (49.9 ±0. 9) % and (50.4 ± 1.9) % respectively. The proportion of specific cytotoxic activity in antigen-DC-CIK was higher than in DC-CIK and CIK. Conclusion The major eytotoxic activity of CIK against gastric cancer cells is non-specific, and specific cytotoxic activity only accounts for 4.9%. After induction of CIK by DC ,the total cytotoxic activity was enhanced and the ma-jor cytotoxic activity is non-specific, and specific cytotoxie activity was enhanced slightly to 5.1%. After in-duction of CIK by antigen-pulsed DC, the major cytotoxic activity is still non-specific, and the specific cyto-toxic activity was largely increased to 30.5%. Key words: Stomach neoplasm; Dendric cells; Killer cells; Antigen