Elevated expression of interleukin-21 and its correlation to T-cell subpopulation in patients with ulcerative colitis

OBJECTIVE: To investigate the expression of interleukin-21 (IL-21) and its correlation to T-cell subpopulation including Th1, Tc1 and Th17 cells in Ulcerative colitis (UC). MATERIAL AND METHODS: We examined the expression of IL-21, IL-17 and IFN-γ in UC patients and controls by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. RESULTS: We found that IL-21 was expressed on CD3(+)CD8(-)T cells by flow cytometry. Plasma IL-21 level and the percentage of CD3(+)CD8(-)IL-21(+) T cells were significantly elevated in UC patients compared to controls. The percentage of CD3(+)CD8(-)IL-17(+) T (Th17), CD3(+)CD8(-)IFN-γ(+) T (Th1) and CD3(+)CD8(+) IFN-γ(+) T (Tc1) cells was also significantly increased in UC patients. Moreover, we found a significant positive correlation between CD3(+)CD8(-)IL-21(+)T cells and Th17 cells. CONCLUSIONS: Elevated IL-21 and its positive correlation to Th17 cells may play a role in the pathogenesis of UC.