CD8A and neoplasm: They went on to show that the anti-CD277 mAb 20.1 (used in immobilized form in previous studies to demonstrate co-stimulatory activity on CD4 and CD8 αβ T cells69) could selectively activate Vδ2Vγ9 T cells when added in soluble form together with interleukin-2 to peripheral blood mononuclear cells, and furthermore sensitized a broad range of tumor cells to killing by γδ T cells17.