FoxP3-expressing T regulatory cells in atopic dermatitis lesions

Recently, studies were conducted to evaluate the impact of T regulatory (T regs) cells in the pathophysiology of atopic dermatitis (AD). The aim of this study was to investigate whether natural T regs are present in AD skin lesions. We performed skin biopsies in 12 adult patients affected by moderate-to-severe AD and 4 healthy volunteers. The specimens were stained immunohistochemically with anti-human CD25 and forkhead/winged helix transcription factor (FoxP3). Double immunostaining for CD25 and FoxP3 was performed also. CD25⁺ cells strongly infiltrated the perivascular and papillar dermis of all lesional specimens, and FoxP3⁺ cells were distributed in the perivascular and interstitial AD dermis, and some cells also infiltrated the dermoepidermal junction and the basal and suprabasal epidermal layers. All healthy skin specimens showed weak CD25 and FoxP3 stainings. Double immunostaining showed that CD25⁺ FoxP3⁺ cells were distributed in the perivascular, interstitial, and periadnexal dermis, and healthy skin specimens featured few CD25⁺ FoxP3⁺ cells scattered throughout the dermis. The past and present data show that an impaired function of natural T regs may not play a primary role in the pathophysiology of AD lesions.