VSIR and neoplasm: When CD8+ T cells from OT-1 mice were co-incubated with ID8 cells with or without VISTA expression, higher levels of target cell lysis were observed in cultures with ID8-control cells than in those with ID8-VISTA cells, indicating that VISTA in tumour cells inhibits antigen-specific cytolysis of OT-1 CD8+ T cells (Fig. 4b).