Serum and cerebrospinal fluid levels of cytokines in acute encephalopathy associated with human herpesvirus-6 infection

Human herpesvirus-6 (HHV-6) is a causative agent of exanthema subitum. The immunological pathogenesis of acute encephalopathy associated with HHV-6 infection is still unclear. We measured the concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), IL-4, IL-6, IL-10, and soluble TNF receptor 1 (sTNFR1) in serum and cerebrospinal fluid (CSF) during the acute stage in 15 infants with acute encephalopathy and 12 with febrile seizures associated with HHV-6 infection. The serum IL-6, IL-10, sTNFR1, CSF IL-6, and sTNFR1 levels of infants with encephalopathy who had neurological sequelae (n = 9) were significantly higher than those with febrile seizures (p = 0.011, 0.043, 0.002, 0.029, and 0.005, respectively). In acute encephalopathy, serum IL-6, sTNFR1, and CSF IL-6 levels in infants with neurological sequelae were significantly higher than those without (n = 6) neurological sequelae (p = 0.043, 0.026, and 0.029, respectively), and serum IFN-γ, IL-6, IL-10, and sTNFR1 levels were significantly higher than those in the CSF (p = 0.037, 0.037, 0.001, and 0.021, respectively). There were no significant differences in serum or CSF cytokine levels between infants who were positive for HHV-6 DNA in the CSF (n = 6) compared to those who were negative (n = 9). We suggest that cytokines mediate the pathogenesis of acute encephalopathy associated with HHV-6 infection, and that the elevated levels of serum IL-6, sTNFR1, and CSF IL-6 are important for predicting neurological sequelae.