Immune checkpoint status and exhaustion‐related phenotypes of CD8+ T cells from the tumor‐draining regional lymph nodes in breast cancer

Abstract

Abstract Background Functional status of T cells determines the responsiveness of cancer patients to immunotherapeutic interventions. Even though T cell‐mediated immunity is inaugurated in the tumor‐adjacent lymph nodes, peripheral blood has been routinely sampled for testing the immunological assays. The purpose of this study is to determine the immune checkpoint molecule expression and the exhaustion‐related phenotype of cytotoxic T cells in the regional lymph nodes from breast cancer patients. Patients and methods Multicolor immunophenotyping was used to determine the expression of PD‐1, TIM‐3, LAG3, CTLA‐4, CCR7, CD45RO, CD127, CD25, CXCR5, and ICOS molecules on CD3+CD4−CD56−CD8+ cytotoxic T cells freshly obtained from the lymph nodes and the peripheral blood samples of the breast cancer patients. The results were assessed together with the clinical data. Results A population of cytotoxic T cells was noted with high PD‐1 and CXCR5 expression in the lymph nodes of the breast cancer patients. Co‐expression of PD‐1, CXCR5, TIM‐3, and ICOS indicated a follicular helper T cell (Tfh)‐like, exhaustion‐related immunophenotype in these cytotoxic T cells. Only a minor population with CTLA‐4 and LAG3 expression was noted. The PD‐1+CXCR5+ cytotoxic T cells largely displayed CD45RO+CCR7+ central memory markers. The amount of CXCR5‐expressing PD‐1− cytotoxic T cells was elevated in the lymph nodes of the patients. Conclusion The regional lymph nodes of breast cancer patients harbor Tfh‐like exhausted cytotoxic T lymphocytes with high PD‐1 and TIM‐3 checkpoint molecule expression. The immunological conditions in the regional lymph nodes should be implicated for immune checkpoint immunotherapy (ICI) of cancer.

Keywords

• breast cancer
• cancer biology
• microenvironment
• surgical oncology