Expression of Dopamine Receptors in Immune Regulatory Cells.

OBJECTIVE: Parkinson's disease (PD) patients are usually treated with L-dopa and/or dopaminergic agonists, which act by binding five types of dopaminergic receptors (DRD1-DRD5). Peripheral immune cells are known to express dopamine receptors on their membrane surface, and therefore they could be directly affected by the treatment. Regulatory cells are the main modulators of inflammation, but it is not clear whether dopaminergic treatment could affect their functions. While only regulatory T cells (Tregs) have been proved to express dopamine receptors, it is not known whether other regulatory cells such as CD8regs, regulatory B cells (Bregs), tolerogenic dendritic cells, and intermediate monocytes also express them. METHODS: The expression of dopamine receptors in Tregs, CD8regs, Bregs, tolerogenic dendritic cells, and intermediate monocytes was herein evaluated. cDNA from 11 PD patients and 9 control subjects was obtained and analyzed. RESULTS: All regulatory cell populations expressed the genes coding for dopamine receptors, and this expression was further corroborated by flow cytometry. These findings may allow us to propose regulatory populations as possible targets for PD treatment. CONCLUSIONS: This study opens new paths to deepen our understanding on the effect of PD treatment on the cells of the regulatory immune response.