The Presence of Non-Exhausted Senescent T Cells in Breast Cancer Patients

OBJECTIVE: This study aimed to investigate the presence of cancer-associated senescent T cells in breast cancer patients and the impact of the progression of age on their senescent phenotypes. METHODS: The exhausted T cell lineage was excluded from the analysis of T cells by using PD1 marker. The percentages of CD28- cells were used to determine the senescent phenotype, in which the CD57 expression was used to further characterize their phenotypes. The flow cytometry was used on CytoFLEX flow cytometer and analysed with CytExpert analysis software. RESULTS: In this study, both senescent and non-exhausted senescent T cells were significantly increased in breast cancer patients. However, non-exhausted T cells could demonstrate more significant proportion of senescent T cells, and these phenotypes in CD8+ T cells were increased in breast cancer patients, which were 53.03% and 37.25% (p<0.001). Moreover, CD28-CD57- cells of non-exhausted CD8+ T cells were increased irrespective of age, while the increase in CD28-CD57+ cells was positively correlated with the progression of age (r=0.353, p=0.015). In addition, the predominant CD28-CD57- cells were attenuated after 52 years of age. CONCLUSION: The presence of non-exhausted senescent T cells seemed to be a concern regarding immune dysfunction in breast cancer patients. These phenotypes were presented in both young-age and old-age breast cancer, but the terminal phenotype seemed to be abundant in the elderly.