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.