Role of CD4+CD25high+FOXP3+ Regulatory T Cells in Psoriasis

Background: CD4(+)CD25(high+) regulatory T cells (Tregs) are considered to be of vital importance for maintaining immunologic self-tolerance and preventing autoimmune diseases. These cells have been found to be deficient in skin lesions and in the peripheral blood of patients with psoriasis. Objective: To investigate the role of Tregs in the pathogenesis of psoriasis and to evaluate the changes in Tregs in relation to the severity and the clinical course of psoriasis. Methods: Immunohistochemistry (CD3, 4, 8, 79 and FOXP3) was performed in 22 psoriatic patients compared to 5 normal controls. Flow cytometry (CD3, 4, 8, 25 and FOXP3) was performed in 18 psoriatic patients and 8 normal volunteers and reverse transcriptase polymerase chain reaction (foxp3 mRNA) was performed in 8 psoriasis patients. Results: An increase in the FOXP3(+) cell fraction was detected in the lesional psoriatic skin irrespective of the severity of psoriasis as compared with the normal skin. However, a decrease in FOXP3(+) cells was observed in the samples obtained from psoriasis of 'acute course'. FOXP3(+) Treg populations in the blood of the 'acute course' psoriasis was not different compared to that of 'chronic course' psoriasis and normal controls. Conclusion: The deficiency of FOXP3(+) Tregs in the lesional psoriatic skin might be responsible for the exacerbation of psoriasis. (Ann Dermatol 22(4) 397 similar to 403, 2010)