CD48 may serve as an accessory molecule for the activation of a subset of human gamma/delta T cells

Translating Unconventional T Cells and Their Roles in Leukemia Antitumor Immunity

Recently, cell-mediated immune response in malignant neoplasms has become the focus in immunotherapy against cancer. However, in leukemia, most studies on the cytotoxic potential of T cells have concentrated only on T cells that recognize peptide antigens (Ag) presented by polymorphic molecules of the major histocompatibility complex (MHC). This ignores the great potential of unconventional T cell populations, which include gamma-delta T cells (γδ), natural killer T cells (NKT), and mucosal-associated invariant T cells (MAIT). Collectively, these T cell populations can recognize lipid antigens, specially modified peptides and small molecule metabolites, in addition to having several other advantages, which can provide more effective applications in cancer immunotherapy. In recent years, these cell populations have been associated with a repertoire of anti- or protumor responses and play important roles in the dynamics of solid tumors and hematological malignancies, thus, encouraging the development of new investigations in the area. This review focuses on the current knowledge regarding the role of unconventional T cell populations in the antitumor immune response in leukemia and discusses why further studies on the immunotherapeutic potential of these cells are needed.

Molecular Determinants of Target Cell Recognition by Human γδ T Cells

The unique capabilities of gamma-delta (γδ) T cells to recognize cells under stressed conditions, particularly infected or transformed cells, and killing them or regulating the immune response against them, paved the way to the development of promising therapeutic strategies for cancer and infectious diseases. From a mechanistic standpoint, numerous studies have unveiled a remarkable flexibility of γδ T cells in employing their T cell receptor and/or NK cell receptors for target cell recognition, even if the relevant ligands often remain uncertain. Here, we review the accumulated knowledge on the diverse mechanisms of target cell recognition by γδ T cells, focusing on human γδ T cells, to provide an integrated perspective of their therapeutic potential in cancer and infectious diseases.

Effect of nuclear factor kappaB inhibition on tumor cell sensitivity to natural killer-mediated cytolytic function

Inhibition of the transcription factor NF-kappaB has been reported to increase cell sensitivity to TNF and some cytotoxic drugs. We investigated the effect of NK-kappaB inhibition on the susceptibility of tumor cells to freshly isolated, nonactivated, human NK cells and to a TCRgamma/delta T cell clone displaying an MHC-unrestricted "NK-like" lysis. Using electrophoretic mobility shift assay, we first demonstrated that NF-kappaB/DNA binding activity was induced in target cells following coculture with NK cells or TCRgamma/delta T cell clone. To investigate the effect of target cell NF-kappaB inhibition on NK-mediated lysis, we blocked NF-kappaB translocation by introducing a human cDNA coding for a mutated IkappaB-alpha. Interestingly, our results indicated that inhibition of NF-kappaB did not induce any increase in either granzyme-dependent non-MHC-restricted cytotoxicity mediated by fresh non-stimulated NK cells and by TCR gamma/delta T cell clone or in CD95-mediated lysis. These results emphasize that NF-kappaB expressed in target cells does not play a role in the molecular process related to the control of target cell susceptibility to NK-mediated lysis and suggest that the NF-kappaB pathway is not a general mechanism for controlling the cytotoxic response.