Suppression of IL-10 production by calcitriol in patients with multiple sclerosis

•Calcitriol suppressed cytokine production from peripheral blood mononuclear cells.•Suppression of IL-10 by calcitriol is stronger in MS patients.•Suppression of IL-12/23(p40) by calcitriol is weaker in MS patients.•Suppression of IL-10 by calcitriol was negatively correlated with MS severity.•The anti-inflammatory response to vitamin D may be suppressed in MS patients.

We investigated whether calcitriol (1,25-dihydroxyvitamin D) differentially modulates cytokine production by peripheral blood mononuclear cells from multiple sclerosis (MS) patients compared with that from healthy controls. In response to phytohemagglutinin (PHA) or lipopolysaccharide (LPS), cytokine level in a calcitriol-added sample was normalized to that in a calcitriol-absent sample, and this relative unit was compared. The relative unit of IL-12/23(p40) in LPS-stimulation was higher in MS patients. Moreover, the relative unit of IL-10 in PHA-stimulation was lower in MS patients, and negatively correlated with the Expanded Disability Status Scale. The anti-inflammatory response to vitamin D may be reduced in MS.