T Cell Exhaustion and Senescence in Epstein-Barr Virus-Associated Lymphoma Patients

Background The Epstein-Barr Virus (EBV) is tumorigenic, and can be detected in many kinds of lymphomas. Some studies have shown a worse prognosis for patients with EBV-associated lymphoma. However, the mechanism is not fully understood. This study aimed to investigate the T cell signatures in patients with EBV-associated lymphoma. Methods Peripheral blood was collected from 17 patients with EBV-associated lymphoma and 19 healthy donors. We first examined the proportions of the lymphocyte subpopulations in peripheral blood mononuclear cells in patients with both groups by flow cytometry. Then we employed the enzyme-linked immunospot assay to evaluate the EBV antigen-specific response of the cytotoxic T cells in the two groups. Finally, to explore the mechanism of T cells dysfunction in EBV-associated lymphoma, we examined the expression of multiple inhibitory receptors representing T cell exhaustion and biomarkers representing T cell senescence on the surfaces of CD4+ T cells and CD8+ T cells. Results The ratio of peripheral CD4+ T cells and the absolute cell counts of CD4+ T cells and CD8+ T cells were significantly decreased in patients with EBV-associated lymphoma compared with those of healthy donors. The IFN-γ production upon stimulation of EBV mixed peptides were remarkably reduced in the patients. Higher expression levels of T cell exhaustion markers, PD1, LAG3, TIM3 and CTLA4 on T cells were found in the patients. The two subsects of exhausted T cells (T-bethiPD1mid and EOMEShiPD1hi) were higher in the patients. More importantly, CXCR5+CD8+T cells controlling viral replication decreased significantly in the patients. The fractions of senescent T cells increased in the patients. Conclusions In summary, our study demonstrated that the reduced EBV-specific T cells, the exhaustion and senescence of T cells together contributed to the T cell dysfunction in the patients with EBV-associated lymphoma.