Abstract: ObjectiveTo investigate the effect of umbilical cord blood dendritic cells (DCs) induced by gastric cancer antigen combined with cytokine induced killer (CIK) cells in gastric cancer cell lines SGC7901 in vitro. MethodsMononuclear cells from umbilical cord blood were used to create DCs and CIKs. The cell surface antigen expression of the mature DCs such as CD83, CD86, CD11c and the cell surface antigen of CIKs such as CD3, CD56, CD4, CD8, CD16 were detected using flow cytometry. Sensitized DCsCIKs, DCsCIKs, CIKs as effective cells, and SGC7901 as target cells, the killing activities of these effective cells were tested with LDH release, which the number ratio of cells between effective cells and SGC7901 cells were 10∶1, 20∶1, 40∶1, respectively. ResultsThe cell surface antigen expressions of the mature DCs, such as CD83+CD86+, CD11c+CD83+, CD86+CD11c+ were （75.4±2.1）%, （79.3±1.4）%, （80.2±2.6）%, respectively. The mature sensitiveDCs surface antigen expressions, such as CD83+CD86+, CD11c+CD83+, CD86+CD11c+, were （77.7±1.5)%, (82.6±1.9)%, (76.9±2.6)%, respectively. There was no statistical significance about the surface antigen expression between DCs and  sensitiveDCs （t=1.526, P＞0.05; t=0.958, P＞0.05; t=1.049, P＞0.05）. The CIKs surface antigen expressions, such as CD4+, CD8+, CD3+CD56+CD16+, were (22.8±1.3)%, (77.3±1.8)%, (24.5±2.1)%, respectively. The results suggested that the killing effect of the three kinds of combination cells on gastric cancer cells was different. The number ratio of cells between sensitiveDCs and SGC7901 cells were 10∶1, 20∶1, 40∶1, which the killing activities of sensitiveDCsCIKs against SGC7901 were (37.68±1.49）%, (41.67±0.90）%, (42.71±0.98）%, respectively. The killing activity of sensitiveDCsCIKs was the highest when the ratio of cells between sensitiveDCs and SGC7901 cells were 40∶1. The killing activities of  DCCIKs were (36.77±0.46）%, (38.94±0.95）%, (41.15±0.89）%, respectively.  The killing activities of  CIKs  were （34.74±1.01）%, （37.76±0.43）%, （39.65±0.79）%, respectively. There were statistically significant differences among the three groups （F=5.92, P＜0.05; F=19.13, P＜0.05; F=8.88, P＜0.05）. ConclusionThe tumor killing activity of CIK is enhanced obviously by umbilical cord blood DCs which is sensitized by gastric cancer tumor antigen. There is the highest killing activity when the number ratio of cells between sensitiveDCCIK and SGC7901 cells is 40∶1.

Key words: Stomach neoplasms, Dendritic cells, Killer cells, lymphokineactivated