Background: Subacute sclerosing panencephalitis (SSPE) is a rare progressive inflammatory disease characterized by the persistent infection of the brain by the measles virus. However, the immunological pathophysiology of SSPE is still unclear. Methods: We measured the concentrations of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), IL-4, IL-6, IL-10, and soluble TNF receptor 1 (sTNFR1) in the serum and cerebrospinal fluid (CSF) of 23 patients with SSPE in Papua New Guinea (PNG), a country with a high incidence of SSPE, and Japanese controls by cytometric bead array or ELISA. Results: The serum IL-6 and IL-10 levels of SSPE patients were significantly higher than those of controls (p = 0.0075, and p = 0.0019, respectively). The serum IL-6 and IL-10 levels of SSPE patients with fever were significantly higher than those without fever (p = 0.0107, and p = 0.0006, respectively). The CSF IL-6 levels of SSPE patients were significantly higher than those of controls (P = 0.0218). The CSF IL-6 levels of SSPE patients with myoclonic jerks were significantly higher than those without myoclonic jerks (p = 0.0189). There were no differences in serum IFN-gamma, TNF-alpha, IL-2, IL-4, and sTNFR1, or CSF IFN-gamma, TNF-alpha, IL-2, IL-4, IL-10, and sTNFR1 levels between the affected patients and controls. Conclusion: Our present study suggests that serum IL-6 and IL-10 levels are related to fever, and the CSF IL-6 level, myoclonic jerks, in SSPE patients in PNG. (c) 2005 Elsevier Ltd. All rights reserved.