Secretion of the chemokine interleukin-8 during Japanese encephalitis virus infection

Japanese encephalitis (JE) virus infection induces infiltration of neutrophils in neural as well as extraneural tissues in patients. As interleukin-8 (IL-8) has inflammatory properties, the present study was undertaken to investigate the IL-8 concentrations in cerebrospinal fluid (CSF) and serum from patients with JE and correlate them with neutrophil counts. IL-8 was measured in the CSF or serum of 30 patients with confirmed JE. The majority (92%) of the acute CSF samples showed raised levels of IL-8 with raised numbers of polymorphonuclear leucocytes. Similarly, significantly higher serum IL-8 concentrations were detected in the acute phase of illness than in convalescent JE patients or normal healthy controls. Twenty-one of 25 patients with high concentrations of IL-8 showed significantly increased neutrophil counts in acute phase sera. A gradual decline in neutrophil counts was observed in the convalescent phase of patients who recovered. There was a significant correlation between IL-8 level and the severity of illness, as all severely ill and fatal cases showed higher levels of IL-8 in acute CSF or serum than the levels found in those who recovered. IL-8 concentrations remained high for a longer period in patients with prolonged severe illness than in those who made a complete recovery.