Elevation of Gas6 protein concentration in cerebrospinal fluid of patients with chronic inflammatory demyelinating polyneuropathy (CIDP)

INTRODUCTION: Gas6 enhances survival of Schwann cells and neurons in vitro and participates in autoimmunity in animal models. Since its concentration in human cerebrospinal fluid (CSF) is unknown, we measured it in samples from patients with non-inflammatory/non-autoimmune neurological diseases (NINAD) and autoimmune polyneuropathies. MATERIALS AND METHODS: Samples collected after informed consent during diagnostic lumbar puncture in the period 1999-2006 were stored at -30 degrees C. We considered subjects with NINAD (stroke, ALS, headache, psychiatric conditions simulating neurological diseases, otologic dizziness) or with Guillain-Barré syndrome (GBS) or CIDP. CSF and plasma total protein and age were obtained from clinical records. Gas6 was measured with an ELISA developed and validated in our laboratory (inter-, intra-assay CVs <10%, recovery 96%). Variance, Tukey's post-hoc test, regression were calculated with a statistical software (Statsoft). RESULTS: Mean Gas6 concentration in patients with NINAD was 6.5+/-2.4 ng/ml, 7.2+/-2.6 ng/ml in GBS and significantly higher (11.5+/-1.7 ng/ml) in CIDP than in the other conditions (post-hoc, p<0.005). It was not related to age, CSF total proteins or to CSF/plasma ratio of total proteins (regression, p>0.1). CONCLUSIONS: Gas6 is detectable in CSF and may be involved in chronic autoimmune demyelination or myelin repair.