The first-round co-culture with 231.CD3 aimed to upregulate the expression of PD-1 on naive T cells (Additional file 1: Figure S6) leading to tumor cells resistance to CTL-mediated lysis, then IFN-γ secreted from T cells was measured during a second round of exposure to 231.CD3 with or without HAC at low E:T ratio (1:5) [35]. The gene discussed is IFNG; the disease is neoplasm.