Gamma-delta T cells in glioblastoma immunotherapy

Conventional immunotherapy in the treatment of glioblastoma (GBM) has essentially produced no significant advantage over the use of chemotherapeutic drugs. A strongly immunosuppressive tumor microenvironment and lack of antigen-presenting major histocompatibility expression on tumor cells have made GBM a poor immunological target. Molecular heterogeneity of GBMs, both within the tumor and across patients, results in the immunological escape of tumors that do not express target antigens. Therefore, the development of nonconventional immunotherapy for GBM is continuously being sought. γδ T cells are a minor subset of the human T-cell repertoire with unique antitumor properties that have been shown to be functionally superior to conventional αβ T-cell receptor expressing T cell-based immunotherapy for cancer, including GBM. Unlike, the more abundant αβ T cells, γδ T cells do not require major histocompatibility proteins for activation. In addition to the γδ T-cell receptor, these cells express a plethora of other antigenic receptors that recognize external stimuli, as well as several self-peptides, which make these cells a strong candidate for the development of cancer immunotherapeutics. A higher threshold of activation-induced cell death and resistance to inducing graft-versus-host disease are also characteristics of these T cells. In this review, we discuss the biology and immunological characteristics of γδ T cells and review current research using γδ T cells in GBM immunotherapy to explore whether these cells can be the potential next-gen immunotherapeutic candidate for this dreadful disease.