Study of the biological features of in vitro cultured γδ T cells.

The aim of the present study was to investigate the biological features of in vitro cultured γδ T cells. The γδ T cells were in vitro cultured and on different culture days cell proliferation, phenotype, killing activity and the secretion of cytokines were analyzed. Cell numbers were counted by an automated cell counter, phenotype of the cells and cytokines were analyzed by flow cytometry, and killing activities of the cells against gastric cancer SGC-7901 cells were tested using the cell counting kit-8. From days 7 to 14, in vitro cultured γδ T cells enter the exponential phase. On day 14, maximum proliferation fold was observed, and on day 10, the maximum specific growth rate µmax was achieved. Flow phenotype cluster of differentiation 3+-T-cell receptor γδ+ of the γδ T cells in the first 7-17 days achieved a higher proportion and showed no significant differences between 10 days. Secretion of the cytokines interferon-γ and tumor necrosis factor-α gradually increased in the first 7-14 days. The maximum was achieved on day 14, and subsequently began to decrease. The cytolytic activity of the γδ T cells to kill the SGC-7901 cells in the first 7-14 days had an improved killing effect, a slight decline from the first 17 days; in the effector cell to target cell (E:T) ratio 20:1, 10:1 and 5:1 conditions, γδ T cells kill SGC-7901 cells more effectively than 1:1 and 1:2. In conclusion, γδ T cells cultured in the first 7-14 days are suitable for clinical transfusion, and the optimal transfusion time is day 10. An E:T ratio >5:1 is preferred.