[Blockade of D1-like dopaminergic receptors suppresses Th17-cell function in multiple sclerosis]

To investigate the direct effect of D₁-like dopaminergic receptors antagonist on Th17-cells function in multiple sclerosis (MS) in vitro.

Forty-one relapsing-remitting MS patients and twenty-five healthy subjects were examined. The functional activity of Th17-cells was assessed by the ability to produce IL-17 and IFN-γ by peripheral blood mononuclear cells (PBMCs) and CD4⁺ T cells, stimulated with microbeads coated with anti-CD3/anti-CD28-antibodies. To study the involvement of D₁-like dopaminergic receptors in modulation of Th17-cell function, the samples of PBMCs or CD4⁺ T-cells were cultured in the presence of dopamine and/or specific D₁-like dopaminergic receptors antagonist (SCH23390). Cytokine levels in cell culture supernatants were measured by ELISA.

The production of IL-17 and IFN-γ by stimulated PBMCs were higher in MS patients during relapse than in MS patients during clinical remission or in healthy subjects. The production of cytokines by stimulated PBMCs or CD4⁺ T-cells in MS patients during clinical remission and healthy subjects was comparable. Dopamine reduced the production of cytokines by PBMCs and CD4⁺ T-cells in all groups. Blockade of D₁-like dopaminergic receptors did not affect the dopamine-mediated cytokine suppression in MS patients and healthy subjects. Blockade of D₁-like dopaminergic receptors directly suppressed cytokine production by PBMCs and CD4⁺ T-cells in MS patients and healthy subjects.

Dopamine and blockade of D₁-like dopaminergic receptors have an inhibitory effect on Th17-cell function in MS. The activation of D₂-like dopaminergic receptors could mediate the inhibitory effect of dopamine on Th17-cells.