CD4 and Epstein-Barr virus infection: Functional polymorphisms of key cytokine genes with key roles in early immune response, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10) and interferon-γ (IFN-γ), were revealed to have important impacts on the severity and duration of disease and disease outcome after acute EBV infection.21 It has been suggested that interferon could reduce levels of IL-6 and TNF-α by regulating the action of pro-inflammatory cytokines induced by CD4+ and CD8+ T-lymphocytes22, and played an anti-inflammatory role in IM.