Matrix metalloproteinases are involved in leucocyte invasion into the central 
nervous system (CNS) during meningitis. The aim of the study was to determine 
whether there are differences in the expression patterns of matrix 
metalloproteinase-9 (MMP-9) and the tissue inhibitor of metalloproteinase-1 
(TIMP-1) in the cerebrospinal fluid (CSF) of patients with meningitis caused by 
one of two known distinct viral agents. Concentrations were measured by using an 
enzyme-linked immunosorbent assay (ELISA) in 16 children with mumps meningitis, 
in 25 children with echovirus type 30 meningitis and in a control group of 23 
children without any CNS infection. Increased levels of MMP-9 were found in 
children with mumps (median 0.48 ng/ml; P < 0.001) and enteroviral meningitis 
(median 2.76 ng/ml; P < 0.001) compared with that in controls (median: 0.01 
ng/ml). Concentrations of TIMP-1 greatly exceeded concentrations of MMP-9 and 
were elevated in children with mumps (median: 56 ng/ml) and echovirus type 30 
meningitis (median: 55 ng/ml) compared to controls (median: 17 ng/ml). No 
significant differences in MMP-9 or TIMP-1 levels were detected between the two 
meningitis groups. The MMP-9/TIMP-1 ratio was greater in children with echovirus 
type 30 than in those with mumps meningitis. There was no correlation between 
MMP-9 levels and total CSF cell count. MMP-9 correlated with CSF absolute 
neutrophil count in children with echovirus type 30 meningitis (r = 0.431; P < 
0.05). The concentration of MMP-9 is higher in children with viral meningitis, 
possibly because of infiltrating polymorphonuclear cells present in the initial 
phase of the disease.