PERIPHERAL BLOOD-DERIVED, gamma 982 T CELL-ENRICHED CELL LINES FROM GLIOBLASTOMA MULTIFORME PATIENTS EXERT ANTI-TUMORAL EFFECTS IN VITRO

The goal of this work was to assess the potential of T cells expressing V gamma 9V delta 2+ T cell receptors (TCR, gamma 9 delta 2T cells) present in peripheral blood (PB) mononuclear cells (MC, PBMC) of glioblastoma multiforme (GBM) patients to act as anti-tumoral agents. We found that gamma 9 delta 2T cell levels were decreased in patients' PB relative to a cohort of healthy donors (HD) (respectively 0.52 +/- 0.55%, n=16, vs 1.12 +/- 0.6%, n=14, p=0.008) but did not significantly correlate with postoperative survival (R=0.6, p=0.063). Importantly, however, the gamma 9 delta 2T cells could be expanded in vitro to consist 51 +/- 23% of the cultured lymphocytes (98% CD3+). This was achieved after 14 days of culture in medium containing the amino-bisphosphonate (ABP) Zoledronate (Zol) and interleukin (IL)-2, resulting in gamma 9 delta 2T cell-enriched lines (gdTCEL) similar to those of HD derived gdTCEL (54 +/- 19%). Moreover, gdTCEL from patients and HD mediated cytotoxicity to GBM-derived cell lines (GBMDCL), which was abrogated by immune-magnetic removal of the gamma 9 delta 2T cells. Furthermore, low level interferon (IFN) gamma secretion was induced by gdTCEL briefly co-cultured with GBMDCL or autologous - tumor-derived cells, which was greatly amplified in the presence of Zol. Importantly, IFN gamma secretion was inhibited by mevastatin but enhanced by cross-linking of butyrophilin 3A1 (CD277) on a CD277+ GBMDCL (U251MG) or by pretreatment of GBMDCL with temozolomide (TMZ). Taken together, these data suggest that gamma 9 delta 2T cells in PB of GBM patients can give rise to gdTCEL that mediate anti-tumoral activities.