A Study on the Number of Circulating CD4+CD25+Foxp3+ Regulatory T Cells and CD4+CD25-Foxp3+ T Cells in Psoriasis

Song, Sang Hyun; Kim, Dong Jin; Na, Chan Ho; Kim, Min Sung; Shin, Bong Seok

Abstract

BACKGROUND
Regulatory T cells (Treg) are able to inhibit the immunological response and maintain cutaneous immunological homeostasis, thus preventing autoimmunity against itself. In several studies, the importance of CD4+CD25+Foxp3+ Treg in psoriasis has been examined, using the peripheral blood of patients. However, limited studies on Treg are available and shows conflicting results. Recently, CD4+CD25-Foxp3+ T cells were identified as being the peripheral reservoir of CD4+CD25+Foxp3+ Treg.
OBJECTIVE
The purpose of this study was to investigate differences in the CD4+CD25+Foxp3+ Treg and CD4+CD25- Foxp3+ T cell counts between patients with psoriasis and normal controls.
METHODS
For phenotypic analysis, the proportions and absolute cell numbers of CD4+CD25+Foxp3+ Treg and CD4+CD25-Foxp3+ T cells in the peripheral blood were examined by flow cytometry. The correlation between the CD4+CD25+Foxp3+ Treg count and other parameters (age of onset, disease duration, BSA, psoriasis area and severity index score, and clinical stage) was also analyzed.
RESULTS
Although the CD4+CD25+Foxp3+ Treg count was slightly increased while the number of CD4+CD25- Foxp3+ T cells was slightly decreased in psoriasis patients than that of the controls, the differences between the groups were not statistically significant (5.27+/-2.60 vs. 4.70+/-1.35, p>0.05; 1.56+/-1.07 vs. 1.93+/-1.08, p>0.05). The CD4+CD25+Foxp3+ Treg count did not correlate with the tested parameters except for the clinical stage of psoriasis. The mean+/-SD number of CD4+CD25+Foxp3+ Treg in the stable phase was higher than that in the progressive phase (7.26+/-2.58 vs. 4.35+/-2.10, p<0.05). The CD4+CD25-Foxp3+ T cell count did not show any significant correlation with all the parameters tested (p>0.05).
CONCLUSION
These findings suggest that the CD4+CD25+Foxp3+ Treg count alone is insufficient to explain the pathogenesis and severity of psoriasis. However, a decrease in circulating CD4+CD25+Foxp3+ Treg is likely to be correlated with an aggravation of psoriasis.