To determine whether human CD4(+)CD25(+) cells express glucocorticoid-induced tumor necrosis factor receptor (GITR) and transforming growth factor-beta (TGF-beta) and the difference in CD4(+)CD25(+) cells between patients with inflammatory bowel diseases and healthy subjects, peripheral blood lymphocytes were obtained from patients with ulcerative colitis (UC; n = 50), Crohn's disease (CD; n = 49), and healthy volunteers (control; n = 50) and flow cytometric analysis was performed. In control subjects, the expression of GITR on CD4(+)CD25(+) cells (41.8 +/- 10.5%) was significantly higher than on CD4(+)CD25(-) cells (11.1 +/- 7.4%). Similarly, TGF-beta expression on CD4(+)CD25(+) cells (5.3 +/- 4.6%) was higher than on CD4(+)CD25(-) cells (1.2 +/- 1.4%). There were no significant differences among UC, CD, and control in CD4(+)CD25(+)/CD4(+) ratio. However, there was a significant difference in the CD4(+)CD25(+) TGF-beta+/CD4(+)CD25(+) ratio between active UC and inactive UC (2.7 +/- 2.6 and 7.2 +/- 3.9%, respectively). The results suggest that TGF-beta is involved in the induction or sustained remission of UC.