Prior evidence of cytomegalovirus (CMV) infection has been documented in a large proportion of high-grade brain tumors such as glioblastoma multiforme (GBM), suggesting a potential role for CMV infection in GBM pathogenesis. Vδ2+ γδ T cells, which recognize tumor-derived mevolonate metabolites, have been shown to be highly cytotoxic to GBM cell lines and primary tumor explants. The specific role of Vδ1+ T cells, which respond to CMV infected cells in immunosuppressed patients and recognize NKG2D ligands MIC A/B and UL-16 binding proteins (ULBP), has not previously been investigated.

Vδ1+ T cells were purified (93-95%) from CMV+ and CMV- donors by immunomagnetic selection and cultured on irradiated allogeneic MNC in RPMI + 10% human serum (HS) supplemented with phytohemagglutinin (PHA) and 200U IL-2. Vδ2+ T cells were expanded from mononuclear cells in RPMI/Clicks + 7.5% HS, 1mM Zoledronic acid, and 200U IL-2, all over 14-21 days. Cytotoxicity was assessed by flow cytometry against two primary GBM explants and CMV+/- GBM cell lines U251 and U373. The expression of MIC A/B and UL-16 binding proteins was assessed using flow cytometry.

Vδ1+ T cells from CMV+ donors were significantly more cytotoxic to primary GBM explants than Vδ1+ cells from a CMV- donor (p=0.0021 for GBM 1042 and p= 0.0053 for GBM 1016) but did not significantly differ against CMV+ and CMV- U251 and U373 cells, although CMV infected cells significantly down-regulated ULBP-2 and −3 expression. Blocking of MIC A/B and ULBP-1, −2, and −3 decreased cytotoxicity of γδ T cells by 10-40% based on the expression of the respective antigen. ZOL/IL-2 expanded Vδ2+ T cells were cytotoxic to primary GBM and GBM lines regardless of donor CMV status. These findings suggest that Vδ1+ T cells, particularly Vδ1+ cells expanded from CMV+ donors, recognize GBM independently from Vδ2+ cells and and have a potential role in strategies involving CMV-directed cellular immunotherapy of high-grade brain tumors.

This study was supported by NIH NCI Grant # P50 CA 097247, NINDS Grant # 5R21 NS 57341 and the National Brain Tumor Society Samuel Gerson Leadership Chair.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1942.