CD4+CD25+ Treg cells in patients with toenail onychomycosis.

The essential role played by CD25+CD4+ regulatory T (Treg) cells in the control of immunity against some pathogens such as Helicobacter pylori is now well established. But their role in cutaneous fungal infections is still unknown. Onychomycosis is the chronic fungal infection of the nails, which is very common. The aim of this study was to evaluate possible relationship of CD4+CD25+ Treg cells and onychomycosis. Peripheral blood samples were investigated for CD4+CD25+ Treg cells using flow cytometry analysis in 43 toenail onychomycosis patients and in 30 healthy controls. We have found that onychomycosis patients had a higher expression of CD25+CD4+ Treg cells than controls, with values of 8.45 +/- 4.47% versus 4.64 +/- 1.59%, respectively (P = 0.001). The results of this study suggests that increased numbers of CD4+CD25+ Treg cells may play a role in failure of clearance of dermatophytes from skin by preventing the protective inflammation which is leading to development of onychomycosis. Accordingly, we address the possibility that CD4+CD25+ Treg cells may play a role in immune pathogenesis of other superficial fungal infections.