Problem: Semen mediates expansion of CD4(+) regulatory T cells (Treg) in the murine female reproductive tract. The impact of semen on Treg in humans, however, remains unclear.
Method of study: Using seminal plasma (SP) from 20 healthy donors, we investigated the impact of human semen on CD4(+) T-cell expression of CD127 and CD49d as well as CD4(+) CD127(low) CD49d(low) Treg proliferation, apoptosis, and intracellular expression of FoxP3, TGF-β1, and IL-10.
Results: SP reduced CD4(+) T-cell expression of CD127 and CD49d and increased the proportion of CD127(low) CD49d(low) Treg. This increase was non-proliferative, mediated in part via the conversion of CD4(+) helper T cells into FoxP3(-) but not FoxP3(+) Treg. Additionally, SP induced an increase in intracellular expression of the immunosuppressive cytokine TGF-β1 by the FoxP3(-) but not FoxP3(+) Treg. SP had no impact on Treg intracellular expression of IL-10.
Conclusion: Human seminal plasma fosters the non-proliferative increase in the proportion and immunoregulatory activity of FoxP3(-) Treg.
© 2012 John Wiley & Sons A/S.