Interleukin-6 in cerebrospinal fluid of patients with central nervous system infections

Interleukin(IL)-6 levels were measured in cerebrospinal fluid (CSF) and serum samples from pediatric patients with central nervous system (CNS) infections by means of an enzyme-linked immunosorbent assay. Mean IL-6 concentrations in CSF samples from patients with bacterial meningitis (49,017 +/- 44,730 pg/ml) were significantly higher than those in patients with aseptic meningitis (1076 +/- 1572 pg/ml) or encephalitis (409 +/- 835 pg/ml). In aseptic meningitis and encephalitis, IL-6 levels in serum were within the lower ranges (< 100 pg/ml), in contrast with the highly elevated levels found in bacterial meningitis (14,332 +/- 18,385 pg/ml). In 5 of the 15 patients with encephalitis, elevated levels of IL-6 were observed in the initial CSF samples despite normal findings of routine CSF examinations. Also, sequential CSF samples revealed that there was an increase in the CSF cell count in two of the five patients. These results validated the potential of measuring IL-6 in CSF samples for the purpose of providing additional information on routine laboratory test results.