Background: Regulatory T-Cells (Treg Cells), as one of the immune system components, have been highly effective in the autoimmune diseases prevention, particularly multiple sclerosis (MS). Cytokine-based therapies such as interferon beta-1a (IFN-β1a) is a common drug in MS treatment; however, its exact mechanisms are insufficiently described.

Objective: Therefore, the goal of this study was to evaluate the in vivo impact of IFN-β1a on the Treg Cells in MS.

Methods: In this case-control study, Treg Cells were analysed by flowcytometry in IFN-β1a-treated relapsing-remitting MS (RRMS) in comparison with new cases of MS and healthy subjects.

Results: The frequency of Treg Cells in the IFN-β1a treated-RRMS was increased compared to the new MS cases (P < 0.05). Furthermore, the MFIs of the CD4 and CD25 in T-Cells were significantly reduced in new cases of MS and IFN-β1a-treated RRMS than the control subjects (P < 0.05). Additionally, the FoxP3 MFIs in CD4 + CD25 + T-Cells of IFN-β1a-treated RRMS were significantly lower than the new cases of MS.

Conclusion: Overall, the present study indicated that IFN-β1a as an immunomodulatory drug led to an enhancement in Treg Cells population without CD4, CD25, and FoxP3 molecules upregulation in Treg Cells.