Characterization of Tumor Reactivity of Human Vγ9Vδ2 γδ T Cells In Vitro and in SCID Mice In Vivo

Abstract

Human Vγ9Vδ2 γδ T cells are selectively activated by bacterial phosphoantigens and aminobisphosphonates and exert potent cytotoxicity toward various tumor cells. In this study we have characterized the cytotoxic reactivity of γδ T cell lines established from healthy donors by stimulation with aminobisphosphonate alendronate toward melanoma MeWo and pancreatic adenocarcinomas Colo357 and PancTu1 lines in vitro and in vivo upon adoptive transfer into SCID mice. Lysis of all tumor cells was enhanced when γδ effector cells were preactivated with phosphoantigens. Recognition of MeWo was TCR dependent, as shown by anti-TCR Ab blockade, whereas only the phosphoantigen-mediated increased, but not the basal, lysis of Colo357 and PancTu1 was inhibited by anti-TCR Ab. Furthermore, lysis of Colo357, but not that of MeWo or PancTu1, was completely inhibited by the pan-caspase inhibitor zVAD, indicating different recognition and effector mechanisms involved in the γδ T cell/tumor cell interactions. Upon transfer into SCID mice, alendronate-activated γδ T cells given together with IL-2 and alendronate significantly prolonged the survival of SCID mice inoculated with human tumor cells. The best results were thus obtained when γδ T cells were repetitively given five times over a period of 30 days. With this protocol, human γδ T cells prolonged the mean survival of mice inoculated with MeWo melanoma from 28.5 to 87.3 days (p < 0.0001) and in the case of PancTu1 adenocarcinoma from 23.0 to 48.4 days (p < 0.0001). We conclude that an effective γδ T cell-based immunotherapy might require activation of endogenous γδ T cells with aminobisphosphonate (or phosphoantigen) and IL-2, followed by adoptive transfer of in vitro expanded γδ T cells.

Select Plant Tannins Induce IL-2Rα Up-Regulation and Augment Cell Division in γδ T Cells

“…To circumvent the difficulties inherent in using non-human primates for in vivo studies, efficacy studies have been performed in SCID mice reconstituted with phosphoantigenexpanded human V␦2 T cells. These studies demonstrate phosphoantigen-expanded V␦2 T cell effector function against tumors (45) and bacteria (9). However, challenge studies in immunocompetent animals have not been performed.…”

“…Recently, clinical approaches were developed to expand the number and/or function of human ␥␦ T cells as a potential therapeutic modality for some cancers (44) and to increase innate resistance to infection (7,10). The current phosphoantigen "drugs" expand the major ␥␦ T cell subset found in blood (V␦2), which display potent antitumor cell activity and immune function (13,45,46). However, these drugs have no effect on the tissue-predominant human ␥␦ T cell subset (V␦1) (47).…”

Anti-γδ TCR antibody-expanded γδ T cells: a better choice for the adoptive immunotherapy of lymphoid malignancies

“…Previous studies have shown that lymphoid malignancies can be recognized and killed by phosphoantigen-expanded cd T cells in animal models. 25,26 Aminobisphosphonates, which inhibit the mevalonate pathway by reducing the activity of farnesyl pyrophosphate synthase, promote the intracellular accumulation of isopentenyl pyrophosphate, and activate cd T cells in vitro and in vivo. 5,27 As one of the new-generation aminobisphosphonates, PAM was proven to be a more potent cd T cell stimulus.…”

Direct Costimulatory Effect of TLR3 Ligand Poly(I:C) on Human γδ T Lymphocytes

“…␥␦ T cell clones and lines were established and cultured with occasional restimulation, as previously described (28). V␦1 ␥␦ T cell clones and lines were cultured in 96-well microculture plates coated with 0.5 g/ml anti-CD3 mAb OKT3, and V␦2 ␥␦ T cell clones and lines were stimulated with optimal concentrations of bromohydrin pyrophosphate (BrHPP; 200 nM; provided by Innate Pharma), 0.5 g/ml anti-CD3 mAb, or anti-V␥9 mAb 7A5 (29).…”