Gelsolin concentration in cerebrospinal fluid from patients with multiple sclerosis and other neurological disorders

Background: Gelsolin is a highly conserved intracellular actin‐binding protein with an extracellular isoform, plasma gelsolin, for which there is not yet a clearly defined function. Materials and methods: In this study, we determined gelsolin concentrations in blood and cerebrospinal fluid (CSF) obtained from 25 subjects using immunoblotting and a functional assay that quantifies gelsolin’s ability to accelerate actin polymerization. Results: The gelsolin concentration in CSF, determined by quantitative immunoblotting was 1.2–15.9 μg/ml (average 5.9 ± 3.8 μg/ml). In samples obtained from patients diagnosed with conditions that do not alter standard CSF clinical tests [(idiopathic cephalgia, ischialgia due to discopathy, and idiopathic (Bell’s) facial nerve palsy or entrapment radial neuropathy)], the average gelsolin concentration was 7.2 ± 4.3 μg/ml. In contrast, the gelsolin concentration in samples obtained from patients diagnosed with multiple sclerosis was 2.1 ± 0.7 μg/ml, and a similar low concentration was found in a patient recovering from a subarachnoid hemorrhage. The range of CSF gelsolin concentrations determined by the actin polymerization assay was 0.61–9.97 μg/ml (average 3.6 ± 2.2 μg/ml). These lower values compared with those obtained from immunoblotting analysis suggest that CSF gelsolin may bind other CSF molecules leading to a reduction of its actin‐binding activity. Conclusions: The results presented here show that CSF gelsolin concentration is significantly altered in certain neurological conditions, including multiple sclerosis, indicating the possible utility of CSF gelsolin levels for diagnostic purposes.