Phenotypic difference of tissue-resident memory T cells in solid tumor

Abstract

The presence and clinical importance of tissue-resident memory T (TRM) cells have been recently described in association with various cancer types. However, the frequency and phenotypic characteristics of TRM cells are largely unknown. We analyzed single-cell populations of colorectal cancer (CC, n=18), stomach cancer (SC, n=13), renal cell carcinoma (RCC, n=19), and breast cancer (BC, n=16) by dissociation of tumor tissue with collagenase/hyaluronidase. We investigated populations of naïve, effector, and memory T and TRM cells by flow cytometry. Compared with the other tumor types, CC was associated with a significantly lower percentage of CD8+ T cells (P < 0.001) among CD3+ T cells. Memory T cells were generally the dominant population. Among CD4+ cells, CC was associated with a significantly higher proportion of CD103+ T cells than other tumor types (P < 0.001). Among CD8+ cells, CC and SC were associated with higher CD103+ T cell proportions than RCC and BC (P < 0.001). Significantly more CD8+ than CD4+ cells expressed CD103 (P < 0.001). In association with SC, RCC, and BC, CD8+ T cells had a similar T cell phenotype composition pattern: fewer effector T cells and more memory-type T cells among CD103+ cells compared with CD103- cells (P < 0.05). Immune cell population composition was not significantly associated with pT stage or tumor-infiltrating lymphocyte levels. TRM cell abundance and phenotypes varied among CC, SC, RCC, and BC. Further studies regarding the clinical significance and functional differences of TRM associated with various tumors are warranted.