Induction of apoptosis by cerebrospinal fluid from patients with primary-progressive multiple sclerosis in cultured neurons

Abstract

We have studied the noxious effect of cerebrospinal fluids (CSF) from patients with primary-progressive multiple sclerosis (MS) on cultured neurons. Cells were exposed to CSF for 8 days and the possible neuronal damage was determined. Morphological studies with phase-contrast microscopy showed cellular shrinkage indicating apoptosis. CSF-induced apoptosis as evidenced by the fluorescent DNA-binding dye Hoechst 33342, as well as by the TUNEL-reaction, was only present in primary-progressive MS patients with a worsening disease. This neuron injury did not correlate with blood-brain barrier dysfunction nor with intrathecal IgG synthesis. On the contrary, CSF from either stable primary-progressive or other non-inflammatory neurological diseases, did not induce any culture damage. Undetectable or low similar tumor necrosis factor-alpha (TNF-alpha) levels (range to 8.7 pg/ml) were found in the CSFs tested regardless they damage cultures or not. These results suggest that soluble factors, other than TNF-alpha, molecules transudated from blood or IgG, present in the CSF of active primary-progressive patients with MS induce neuronal apoptosis.