T cell‐mediated tumor cell killing assay

T cells were activated and expanded from peripheral blood mononuclear cells (PBMCs) of healthy donors using Dynabeads^® Human T‐Activator CD3/CD28 (Gibco, 11161D) and IL‐2 (10 ng/ml; Peprotech). To analyze the killing of tumor cells by T cells, we co‐cultured tumor cells with activated primary human T cells in 24‐well plates for 4 days. To visualize the survived tumor cells at the end point, wells were washed with PBS twice to remove T cells, and then, the survived tumor cells were fixed and stained with crystal violet solution. The pictures of the dried plates were taken, and the intensity was quantified.