Animal studies of experimental bacterial meningitis have provided evidence for an involvement of reactive oxygen species (ROS) in the pathophysiology of this disease. Using a lucigenin-enhanced chemiluminescence (CL) method, we tested whether primary rat cerebral endothelial cells can be induced to release ROS upon stimulation with pneumococci. In addition, we determined CSF levels of two markers of lipid peroxidation in patients with bacterial meningitis, compared to patients with viral meningitis and noninflammatory neurological disorders. Malondialdehyde/4-hydroxynonenal concentrations were significantly elevated in CSF samples obtained from patients with bacterial meningitis (23.12+/-5.47 microM), as compared to both control groups (5.43+/-0.18 microM and 7.80+/-0.33 microM, respectively). Cerebromicrovascular endothelial cells, granulocytes, and the macrophage cell line RAW 264.7 (but not astrocytes and neuron-like cells) produced an increase in CL intensity after stimulation with pneumococci. The peak value produced by endothelial cells (500+/-83 cpm) was significantly lower than the maximum CL response in macrophages (1386+/-142 cpm; p<0.05). After addition of superoxide dismutase (SOD), the CL signal returned to baseline values. Equal to the CL technique, nitroblue tetrazolium (NBT) staining of RAW 264.7 showed SOD-inhibitable formazan precipitation when stimulated with pneumococci. In conclusion, this study suggests an important role of endothelial cells in the pathophysiology of bacterial meningitis-namely as a source for ROS production.