Proteomic investigations of the ventriculo-lumbar gradient in human CSF.

Cerebrospinal fluid (CSF) is an ideal biological material in which to search for new biomarkers for improved diagnosis of neurological diseases. During a lumbar puncture between 5 and 15 mL of CSF are obtained. Previous studies have assessed the ventriculo-lumbar concentration gradient of a number of specific proteins. In the present study we took a proteomics approach to investigate the possible concentration gradient of a panel of proteins and peptides in the CSF of 16 patients with neurodegenerative diseases. Using two different mass spectrometry techniques, matrix assisted laser desorption ionization time of flight (MALDI-TOF) and surface enhanced laser desorption ionization time of flight (SELDI-TOF), we found that only one of the investigated proteins, apolipoprotein CI, was significantly decreased between the 1st and the 10th mL of CSF. Furthermore, we confirmed previous results showing a significant decrease in albumin concentration from the first to the last CSF aliquots. In conclusion, we found a significant gradient effect for only two of the measured proteins. However, a standardized procedure for CSF collection for diagnostic and research purposes is crucial to allow comparisons of results between patient groups and between laboratories. This is especially important since CSF is usually collected at several centres and variation in sampled CSF due to pre-analytical factors could complicate the interpretation of the results.