Regulatory role of vitamin D in T-cell reactivity against myelin peptides in relapsing-remitting multiple sclerosis patients

BACKGROUND: Low levels of plasma 25-hydroxyvitaminD (25(OH)D) are associated with a higher incidence of multiple sclerosis (MS) due to the immune suppressive properties of vitamin D. The aim of this study was to determine the correlation between plasma 25(OH)D concentrations and clinical and immunological variables in a cohort of multiple sclerosis patients. METHODS: Plasma 25(OH)D concentrations were evaluated in summer and winter in 15 primary progressive MS (PPMS) patients, 40 relapsing- remitting MS (RRMS) patients and 40 controls (HC). Protocol variables included demographic and clinical data, radiological findings and immunological variables (oligoclonal bands, HLADR15 and T-lymphocyte proliferation to a definite mix of 7 myelin peptides). RESULTS: During the winter, plasma concentrations were significantly lower in RRMS patients compared to HC, whereas no differences were found in summer. No relationships were found between plasma 25(OH)D concentrations and clinical or radiological variables. RRMS patients with a positive T-cell proliferation to a mix of myelin peptides (n = 31) had lower 25(OH)D concentrations. CONCLUSIONS: 25(OH)D is an immunomodulatory molecule that might have a regulatory role in T-cell proliferation to myelin peptides in RRMS patients.