The effect of activated Mϕ1 on γδT cell-mediated killing of gastric cancer cells in vitro

A clear understanding of the interactions between classically activated macrophages (Mϕ1) and γδT cells may improve current therapeutic approaches, including that of immunotherapy for treating certain types of cancer. The present study aimed to expand the current knowledge by showing the effect of culture supernatants of Mϕ1 on the proliferation, cell surface marker expression and tumor suppression effects of γδT cells, and by exploring the potential mechanisms involved. In vitro, Mϕ1 were cultured by GM-CSF and IFN-γ. The isopentenyl pyrophosphate method was used to amplify human peripheral blood γδT cells. The surface markers of macrophages and γδT cells were detected by flow cytometry. The proliferation of γδT cells induced by the culture supernatants of Mϕ1 was investigated using the MTT assay. The lactate dehydrogenase method was used to detect the cytotoxicity of γδT cells on the SGC-7901 gastric cancer cell line. Ten days after cultivation, the percentage of γδT cells from the repertoire of naive cells, expanded from 4.21 to 91.27%. The percentage of cells expressing CD44 was 94%. The percentage of CD68 on cultured Mϕ1 was increased from 17.7 to 73.2%. The culture supernatants of Mϕ1 increased the proliferation of γδT cells compared with the control group (33.8% vs. 0, P<0.01). The culture supernatants of Mϕ1 increased the cytotoxicity of γδT cells compared with the control group (70.18 vs. 47.25%, P<0.01). In conclusion, the supernatant of cultured Mϕ1 promotes the proliferation of γδT cells and their cytotoxic effect on the SGC-7901 gastric cancer cell line.