Human γδ T cells: a nonredundant system in the immune-surveillance against cancer

Down-regulation of expression of MHC alleles, as well as tumor-specific antigens, is observed frequently during tumor progression, resulting in an impairment of MHC-restricted, αβ-T-cell-mediated, tumor-specific immunity. Given the unique set of antigens recognized and the lack of requirement for classical antigen-presenting molecules, γδ T cells might, therefore, represent a nonredundant system in anticancer surveillance, as proposed for the immune response against pathogens. Evidence that γδ and αβ T cells make distinct contributions to anticancer surveillance has been provided recently in mice. Here, we discuss the potential role played by resident Vδ1+ and circulating Vδ2+ T cells in the defense against solid tumors and hematological malignancies.