Evaluation of IL17 Producing Memory Regulatory and Effector T Cells Expressing CD26 Molecule in Patients with Psoriasis

Memory regulatory T cells (Tregs) has been demonstrated to produce IL17 in Psoriasis. Forkhead box P3 (Foxp3) has been demonstrated not to be reliable marker to evaluate Treg cells. Effector CD4^+T cells also express Foxp3 after activation. Human T helper17 cells (Th17) express high level of surface CD26, while regulatory T cells are CD26 negative or low and this phenotype is stable even after activation of Treg cells. In this study, we aimed to analyze IL17 producing Treg cells using CD26. #xA0;Memory T cells were isolated from 10 patients with psoriasis and 10 controls. Ex vivo stimulated IL17 producing regulatory (Forkhead Box P3 (Foxp3)^+CD25^+CD26/low) and effector (Foxp3^+CD25^+CD26hi) memory T cells were analyzed by flow cytometry. IL23, IL6, TNF #x3B1;, TGF #x3B2; and IL17 cytokine levels were also evaluated. No significant difference in IL17^+memory regulatory T cells was seen between patients and controls (p=0.19). A significant decrease in the percentage of IL17 producing CD26hi effector memory T cells was observed in patients (p=0.04). However, the percentage of these cells was not different between patients with mild or severe form of psoriasis compared to controls (p=0.13). We could not find any significant difference regarding IL23, IL6, TNF #x3B1;, TGF #x3B2; and IL17 cytokine levels in plasma and cell culture supernatant samples between patients and controls. #xA0;Taken together, our results showed a reduced IL17 producing effector memory CD26hi T cells in patients with psoriasis compared to controls. However, IL17 producing memory regulatory CD4^+T cells of patients showed no significant difference from that of controls. #xA0;