Thrombopoietin in the Cerebrospinal Fluid of Patients with Aseptic and Bacterial Meningitis

Despite the recent evidence of the localization of thrombopoietin (TPO) and its receptor in the central nervous system (CNS), TPO protein concentrations in the cerebrospinal fluid (CSF) remained to be clarified. We previously reported that serum TPO is increased in children with meningitis. To determine changes in TPO concentrations in the CSF by meningitis and to explore the relationship between serum and CSF TPO concentrations, we measured TPO concentrations in 110 CSF samples and 33 serum/CSF pairs from 11 bacterial meningitis, 49 aseptic meningitis, and 50 nonmeningitis children. In only 12% (13 of 110) of CSF samples (0 bacterial meningitis, 8 aseptic meningitis, and 5 controls), TPO concentrations could be determined (24.1 +/- 29.0 pg/ml). CSF TPO concentrations did not significantly differ among the three groups and did not correlate with age. TPO concentrations in all serum samples were detectable, and mean concentrations in bacterial meningitis (510.6 +/- 237.0 pg/ml) were significantly higher than those in aseptic meningitis (136.6 +/- 71.6, p < 0.01) and controls (181.3 +/- 88.3, p < 0.01). These findings suggest that TPO is not produced in the CNS of patients with meningitis and that TPO did not cross the blood-brain barrier even during meningeal infection.