INTERLEUKIN-2 RECEPTOR-ALPHA AND BETA-CHAIN EXPRESSION BY CIRCULATING ALPHA-BETA AND GAMMA-DELTA T-CELLS IN INFLAMMATORY BOWEL-DISEASE

The pathogenetic role of activated alpha beta and gamma delta T cells in inflammatory bowel disease (IBD) is not well defined. To elucidate this, interleukin-2 receptor (IL-2R) alpha and IL-2R beta single chain expression and coexpression by peripheral blood TCR(alpha beta cells and TCR gamma delta cells was studied in 21 patients with ulcerative colitis (UC), 25 with Crohn's disease (CD), and 15 controls. The percentages of IL-2R alpha+beta-, IL-2R alpha-beta+, and IL-2R alpha+beta+ TCR alpha beta+ cells were increased in IBD patients with moderate and severe disease activity, as compared to controls (P < 0.01). In contrast, the percentages of IL-2R alpha-beta+ and IL-2R alpha+beta+ TCR gamma delta+ cells were increased in patients with inactive UC (P < 0.01), but not in CD. The results suggest that activated alpha beta T cells are involved in the development of IBD. The differences in gamma delta T cell IL-2R expression between inactive UC and CD may correspond to a yet undefined etiopathogenetic difference between these two diseases.