Peripheral EBV antigen-specific T cell is dysfunctional in Epstein–Barr virus positive diffuse large B-cell lymphoma

EBV-positive diffuse large B-cell lymphoma (EBV + DLBCL) is associated with poor prognosis, possibly due to the capacity of EBV to dampen host anti-tumor immunity. Patients' peripheral EBV antigen-specific T lymphocytes may be functional deficiency. This study investigated the mechanisms underlying this deficiency by examining the phenotypes and function of peripheral T cells via ELISPOT and flow cytometry. 6 EBV + DLBCL patients, 54 EBV-negative DLBCL (EBV- DLBCL) patients, and 12 healthy controls were enrolled. We observed significantly reduced IFN-γ secreting T cells in EBV + patients upon EBV peptides stimulation compared to EBV-negative patients (P < 0.001), indicating a dysfunction in EBV antigen-specific T cells. Furtherly, compared to EBV- DLBCL, EBV + DLBCL showed decreased proportions of total lymphocytes (P = 0.005), CD8⁺ T cells (P = 0.004), CD4⁺ T cells central memory (P = 0.017), CD8⁺ T cells naïve (P = 0.001), and CD8⁺ T cells effector (P = 0.031), alongside increased CD4⁺ and CD8⁺ effector memory T cells (P = 0.010 and P < 0.001, respectively). Both CD4⁺ and CD8⁺ T cells demonstrated elevated PD-1 expression (P = 0.045 and P = 0.036, respectively), and the CD4⁺TIM-3^-CTLA-4^- population was reduced (P = 0.049), in EBV + DLBCL. There was also a significant decline in CD28⁺KLRG1^- (P = 0.018) and CD28⁺CD57^-KLRG1^- (P = 0.036) subsets among CD8⁺ T cells in EBV + patients. CD8⁺ T cells showed decreased IFN-γ expression after PMA/BFA stimulation in EBV + DLBCL(P = 0.015). These findings suggested that EBV antigen-specific T cell functional deficits might correlate with altered T cell subset distributions, heightened levels of exhaustion and senescence, and diminished expression of immune effector molecules.