Anti-CD277 mAb induces strong Vγ9Vδ2 T cell cytolytic and cytokine responses. (A) Cytolytic activity of human Vγ9Vδ2 T cells (clone GR4) against Raji Burkitt lymphoma cells. Raji (targets) or Vγ9Vδ2 T (effectors) cells were treated for 2 hours with anti-CD277 mAb (#20.1; 10 μg/mL), washed, and cocultured at the indicated γδ T cell-to-target (E:T) ratios. Data are mean ± SD of triplicate measurements. **P < .005. ***P < .0005. (B) Stainings of CD107a/b (top row; surface) and IFN-γ (bottom row; intracellular) of Vγ9Vδ2 T cells (clone GR4) after coculture with Raji cells, pretreated for 2 hours with either anti-CD277 mAb (#20.1; 10 μg/mL) or NBP (pamidronate; 250μM). Numbers adjacent to outlined areas indicate percent and geometric mean of fluorescence intensity (numbers in brackets) of CD107a/b⁺ and TNF-α⁺ T cells. (C) Expression of CD107a/b on Vγ9Vδ2 T cells (clone GR4) after coculture with human tumor/transformed cell lines (n = 18), pretreated for 2 hours with anti-CD277 mAb (#20.1; 10 μg/mL). The values for the percentage of CD107a/b⁺ Vγ9Vδ2 T cells are represented in the graph. Control indicates no antibody. Data are representative of at least 3 independent experiments.