LYMPHOCYTES IN PATIENTS WITH CHRONIC ACTIVE EPSTEIN-BARR VIRUS INFECTION EXHIBITED ELEVATED PD-1/PD-L1 EXPRESSION AND A PREVAILING TH2 IMMUNE RESPONSE.

Abstract

Background And Objectives: Chronic active Epstein-Barr virus infection (CAEBV) is a lymphoproliferative disorder characterized by the increased numbers of EBV-infected T/natural killer (NK) cells and ongoing symptoms resembling infectious mononucleosis. Nonetheless, the exact correlation between peripheral lymphocyte subsets and the development of CAEBV remains uncertain. Methods: Consequently, we examined the levels of programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) expression, the status of EBV infection, and the frequencies of peripheral lymphocyte subpopulations in 24 patients with CAEBV and 15 EBV-seronegative donors using flow cytometry. Results: Patients with CAEBV showed a notable rise in the expression levels of PD-1 and PD-L1 in peripheral T and NK cells compared to healthy donors (P < 0.05). The induction of PD-L1 expression was attributed to EBV infection. Moreover, most of the T cells infected with EBV displayed a memory phenotype characterized by the presence of CD45RO+. Additionally, patients with CAEBV showed markedly decreased frequency of helper T cells 1 (Th1) and naïve T (Tn) cells, and significantly elevated frequency of Th2 and effector-memory T (Tem) cells. Conclusions: To summarize, EBV might evade the immune system by inducing PD-1/PD-L1 expression in peripheral T and NK cells, and promoting Th2 immune response dominance. Additionally, it may establish long-term persistence by infecting memory T cells in CAEBV.