Background: Psoriasis is a chronic autoimmune inflammatory disease of theskin with strong genetic and environmental risk factors and is regarded as a Th1 cell-type disease. Theaim of our study was to evaluate the effect of one-month PUVA (Psoralen Ultraviolet A) therapy on a regulatoryT-cell subpopulation (CD4+CD25+) and the production of some cytokines. Material/Methods: The study wasperformed on the group of 12 patients with severe psoriasis. They were put on PUVA therapy for one month.We analyzed the level of CD4+CD25+ regulatory T cells using a FACSCalibur cytometer and CellQuest Software.The production of IFN-gamma (interferon-gamma), TNF-alpha (tumor necrosis factor alpha), IL (interleukin)-10, IL-5, IL-4, and IL-2 by lymphocytes was estimated by using a CBA system. The control group consistedof 11 healthy volunteers. Results: We found that the production of INF-gamma, TNF-alpha, IL-2, and IL-10in psoriatic patients before PUVA application increased significantly compared with the control group.In patients after PUVA therapy we observed decreased production of TNF-alpha and a decreased number ofCD4+CD25+ cells in the blood compared with the same group of patients before the treatment. Conclusions:It was demonstrated that systemic PUVA therapy led to a marked reduction in CD4+CD25+ T cells and a changein cytokine production.

Keywords: Cytokines - biosynthesis, PUVA Therapy, Pilot Projects, Psoriasis - immunology, T-Lymphocytes, Regulatory - immunology