Identification of lesional CD4+ CD25+ Foxp3+ regulatory T cells in psoriasis

Background. Depletion of CD4+ CD25+ Foxp3+ naturally occurring regulatory T cells (T-reg) induces autoimmune phenomena. These cells have not yet been fully characterized in the skin of psoriatic patients. Objectives: To prove that the Zenon immunofluorescent labeling technique is suitable for the demonstration of co-localization of T-cell markers and in particular to show the distribution of Treg in psoriatic skin. Methods: In biopsies derived from normal and psoriatic skin, CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+,CD8+ CD45RO+ and CD4+ CD25+ Foxp3+ cells in the dermis and in the epidermis were immunophenotyped, using a quantitative immunofluorescent labeling technique (Zenon), analyzed and compared using image analysis. Results: The immunofluorescent labeling technique was shown to be an easy and reliable tool to demonstrate co-localization of T-cell markers. In psoriasis, all pathogenic T-cell subsets (CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+ and CD8+ CD45RO+ cells) were significantly increased in the dermis and in the epidermis, as compared to normal skin (all p < 0.05). Using this labeling technique we were able to reveal CD4+ CD25+ Foxp3+ T-reg in psoriatic dermis, but not in the dermis of normal skin (p < 0.0001). Conclusions: The Zenon immunofluorescence technique in combination with image analysis is suitable for the demonstration of co-localization of T-cell markers in tissue. Increased numbers of pathogenic T cells (CD4+ CD25+, CD4+ CD45RO+, CD8+ CD25+ and CD8+ CD45RO+) were shown in the dermis and epidermis, whereas CD4+ CD25+ Foxp3+ Tr,g were identified in psoriatic skin with a predilection for the upper dermis. Copyright (c) 2006 S. Karger AG, Basel