Background
Intrathecal interleukin (IL)-6 is considered to be a proinflammatory biomarker for cerebral inflammatory response. This is of clinical importance for the prediction of vasospasm after subarachnoid haemorrhage (SAH). We evaluated a bedside technique for the quantitative measurement of IL-6 in the cerebrospinal fluid (CSF).
Material and Method
32 samples of CSF and serum were taken from 11 patients suffering from SAH on day 3, 4 and 5 after bleeding. A lateral flow immunoassay chip-test (POC-Test) was used for bedside testing and the results were compared to the standard chemiluminescence-based ELISA (Immulite) performed in a specialized laboratory.
Results
For CSF analysis Immulite and POC-Test show linear correlation (r2=0.81). The high IL-6 values found in SAH are depicted more easily by the POC-Test, because it has a working range of up to 10.000 pg/ml instead of up to 1000 pg/ml for Immulite. Serum IL-6 values were clearly lower, suggesting CNS inflammation in SAH.
Conclusions
The new chip-test provides a handy tool for the neurosurgical intensive care unit, analysing CSF IL-6 concentrations within 20 minutes. This is the first time a point-of care test for IL-6 in CSF was evaluated. The test results match the values achieved by the standard Immulite technique. Therefore a tool for clinical routine interleukin-6 investigation is provided which could find use in a broad variety of neurosurgical and neurological diseases.

Keywords: Subarachnoid Hemorrhage - cerebrospinal fluid, Point-of-Care Systems, Luminescence, Interleukin-6 - cerebrospinal fluid, Enzyme-Linked Immunosorbent Assay