Immunoregulatory Effects of Paroxetine in Healthy Volunteers: An In Vitro Investigation

Background: Paroxetine has been a commonly prescribed antidepressant for treatment of major depression and various anxiety disorders for almost 30 years due to its fewer side effects and toxicity compared with its counterparts. Despite several investigations performed, the paroxetine immunoregulatory effect in healthy subjects is still controversial. In this study, the paroxetine effect on the cell proliferation along with IL-4 and interferon-gamma (IFN-γ) secretion in peripheral blood mononuclear cells (PBMCs) of physically and mentally healthy subjects is investigated. Materials and Methods: Blood was drawn from 20 healthy subjects and PBMCs were isolated. Cells were treated with paroxetine and/or phytohemagglutinin (PHA) for 72 h. IL-4 and IFN-γ concentrations were assessed in the supernatant using an enzyme-linked immunosorbent assay. The BrdU cell proliferation assay was also performed to evaluate the paroxetine effect on PBMCs in the absence or presence of PHA. Results: Paroxetine (25 μM) significantly inhibited the production of IL-4 and IFN-γ in PHA-stimulated human PBMC cultures. Surprisingly, paroxetine suppressed cell proliferation in the unstimulated culture in a dose-independent manner. Paroxetine also attenuated cell proliferation in the PHA-stimulated culture, especially at 25 μM concentration. Conclusion: The obtained results suggest that paroxetine can be a potent therapeutic option in inflammatory diseases by balancing immune responses.