Tissue-resident memory T cells at the center of immunity to solid tumors.

Immune responses in tissues are constrained by the physiological properties of the tissue involved. Tissue-resident memory T cells (T cells) are a recently discovered lineage of T cells specialized for life and function within tissues. Emerging evidence has shown that T cells have a special role in the control of solid tumors. A high frequency of T cells in tumors correlates with favorable disease progression in patients with cancer, and studies of mice have shown that T cells are necessary for optimal immunological control of solid tumors. Here we describe what defines T cells as a separate lineage and how these cells are generated. Furthermore, we discuss the properties that allow T cells to operate in normal and transformed tissues, as well as implications for the treatment of patients with cancer.