INFLUENCE OF FILTRATION ON A NEW GLIOTOXIC ACTIVITY IN CEREBROSPINAL-FLUID FROM MULTIPLE-SCLEROSIS PATIENTS

Cerebrospinal fluid (CSF) from patients with relapsing-remitting multiple sclerosis (MS) at relapse causes death of primary astrocytes from rat cortex and of immortalized mouse astroglial cells in culture. CSF from relapsing-remitting MS at remission and chronic-progressive MS patients showed only a weak toxic effect. CSF from other inflammatory or non-inflammatory diseases showed no toxicity. Using a 5-step purification procedure we identified the gliotoxic substance as a 17 kD glycoprotein. The same protein was identified in eluates of proteins retained from CSF1 filters when filtration of CSF from MS patients was performed. Proteins from filters were eluted with 1% SDS, and purification was carried out. Quantification of total toxic activity in CSF before and after filtration by a biological test on immortalized astrocytes using the MTT assay showed that CSF1 filters retain between 50 - 85% of the toxic activity (protein). In multiple filtration experiments the efficiency of retention of the toxicity by filter was approximately the same for each filtration. However, between filtrations the level of toxic protein in the CSF was returned to previous levels in some patients, suggesting that the filter retains the toxic protein itself, but does not eliminate the source of its production. The fact that proteins seeming to play a crucial role in the pathology of MS can be retained on CSF1 filters by in vivo techniques is very encouraging for further devising new clinical strategies for the management of active MS.