The role of regulatory T cells in malignant glioma.

The aggressive nature of gliomas is closely related to their capacity to evade the anti-tumoral immune response. The mechanisms implicated in this phenomenon are only partially understood. A subset of T cells, termed CD4+ CD25+ regulatory T cells (Treg), have been shown to inhibit the actions of effector lymphocytes. These Tregs are increased in the blood and tumors of glioma patients and animals with experimental brain tumors. Moreover, tumor infiltration by Tregs correlates with tumor grade and in animal models, depletion of Tregs is associated with prolonged survival. This review focuses on the role of Tregs in the immune suppression exhibited by malignant gliomas. The biology of these cells is briefly described in this context and finally, potential therapeutic strategies related to Treg ablation are explored.