[HTML][HTML] Phenotype of NK-like CD8 (+) T cells with innate features in humans and their relevance in cancer diseases

A Barbarin, E Cayssials, F Jacomet, NG Nunez… - Frontiers in …, 2017 - frontiersin.org
A Barbarin, E Cayssials, F Jacomet, NG Nunez, S Basbous, L Lefevre, M Abdallah…
Frontiers in immunology, 2017frontiersin.org
Unconventional T cells are defined by their capacity to respond to signals other than the well-
known complex of peptides and major histocompatibility complex proteins. Among the
burgeoning family of unconventional T cells, innate-like CD8 (+) T cells in the mouse were
discovered in the early 2000s. This subset of CD8 (+) T cells bears a memory phenotype
without having encountered a foreign antigen and can respond to innate-like IL-12+ IL-18
stimulation. Although the concept of innate memory CD8 (+) T cells is now well established …
Unconventional T cells are defined by their capacity to respond to signals other than the well-known complex of peptides and major histocompatibility complex proteins. Among the burgeoning family of unconventional T cells, innate-like CD8(+) T cells in the mouse were discovered in the early 2000s. This subset of CD8(+) T cells bears a memory phenotype without having encountered a foreign antigen and can respond to innate-like IL-12 + IL-18 stimulation. Although the concept of innate memory CD8(+) T cells is now well established in mice, whether an equivalent memory NK-like T-cell population exists in humans remains under debate. We recently reported that CD8(+) T cells responding to innate-like IL-12 + IL-18 stimulation and co-expressing the transcription factor Eomesodermin (Eomes) and KIR/NKG2A membrane receptors with a memory/EMRA phenotype may represent a new, functionally distinct innate T cell subset in humans. In this review, after a summary on the known innate CD8(+) T-cell features in the mouse, we propose Eomes together with KIR/NKG2A and CD49d as a signature to standardize the identification of this innate CD8(+) T-cell subset in humans. Next, we discuss IL-4 and IL-15 involvement in the generation of innate CD8(+) T cells and particularly its possible dependency on the promyelocytic leukemia zinc-finger factor expressing iNKT cells, an innate T cell subset well documented for its susceptibility to tumor immune subversion. After that, focusing on cancer diseases, we provide new insights into the potential role of these innate CD8(+) T cells in a physiopathological context in humans. Based on empirical data obtained in cases of chronic myeloid leukemia, a myeloproliferative syndrome controlled by the immune system, and in solid tumors, we observe both the possible contribution of innate CD8(+) T cells to cancer disease control and their susceptibility to tumor immune subversion. Finally, we note that during tumor progression, innate CD8(+) T lymphocytes could be controlled by immune checkpoints. This study significantly contributes to understanding of the role of NK-like CD8(+) T cells and raises the question of the possible involvement of an iNKT/innate CD8(+) T cell axis in cancer.
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