Fig. 4.

Antitumor activity of expanded/activated γδ T-cells demonstrated against human glioma cell line U251MG. (A) Expanded γδ T-cells (G/D T-cells) and expanded αβ T-cells (A/B T-cells) from three separate donors were sorted to >95% purity. U251MG glioma cells were labeled with [⁵¹Cr] and incubated with γδ T-cells (open circles) or αβ T-cells (solid circles) for 4 h at the indicated effector to target (E:T) ratios. Supernatants were removed to determine [⁵¹Cr] release in counts per minute. Data are presented at the mean ± SD percent target lysis from triplicate determinations. (B) Antitumor activity of expanded γδ T-cells against cultured primary human astrocytes, selected GBM cell lines, and primary GBM explant cultures (GBM 1 and 2) at an effector to target ratio of 16:1. Targets were labeled with PKH26 and incubated with γδ T-cells for 4 h at the indicated effector to target ratios. Live:dead ratios were calculated from the percentage of target cells that incorporated the DNA stain To-Pro iodide as determined by flow cytometry. (C) Killing of adherent primary GBM explant cultures at incubation with expanded/activated γδ T-cells as determined by a commercial ATP release assay.