Abstract
Several studies report an impact of the neurotransmitter dopamine (DA) on human immune cells, with effects dependent on the immune cell type addressed and their activation status. Another contributing factor appears to be sex, as sex-specific differences in the dopaminergic pathway are described in the neurological context as well as in autoimmune diseases. However, a deeper understanding of these differences in peripheral immune cells remains limited. In this study, we investigated the effects of dopaminergic stimulation on activation and cytokine secretion of peripheral blood mononuclear cells from women and men using flow cytometry, ELISA, and multiplex assays. We found a B cell-driven downregulation in cytokine secretion of monocytes exclusively from women under physiological conditions in vitro. Moreover, B cells from men showed higher dopamine receptor (DR) expression, which was shown to be further increased by sex hormones only in men. In monocytes from women, an acute inflammatory stimulus via CpG combined with dopaminergic stimulation caused a switch to a proinflammatory phenotype, which was less pronounced in men. These novel findings in sex-specific responses to dopaminergic stimulation are crucial for understanding DA's function in the healthy and activated immune system and provide evidence to treat DA-related pathologies in a sex-specific manner.