The CD4+/CD8+ lymphocyte ratio of the EBV-HLH group was higher than that of the EBV-IM group, indicating that the ability of CD8+ lymphocytes to activate and proliferate was lower in the EBV-HLH group than in the EBV-IM group, and, consequently, the virus clearance ability of the EBV-HLH group was weaker [11]. The gene discussed is CD4; the disease is hemophagocytic syndrome.