OBJECTIVES: Inflammatory bowel disease is characterized by T cell activation. Activated T cells shed interleukin-2 receptors (IL-2R) in a soluble form. A positive correlation between sIL-2R alpha (CD25) and disease activity in inflammatory bowel disease has been shown previously, whereas IL-2R beta (CD122) has never before been investigated in this respect. Serum from 27 patients with ulcerative colitis (UC), 31 with Crohn's disease (CD), and 29 healthy volunteers was obtained.

METHODS: Disease activity was scored according to a semiquantitative score for UC and by Crohn's disease activity index for CD. sIL-2R alpha and -beta chains were assessed by a sandwich ELISA technique using monoclonal antibodies specific for CD25 and CD122, respectively.

RESULTS: The median concentration of sIL-2R alpha was 4424 pg/ml in healthy controls, 6460 in UC (p < 0.004), and 6371 in CD (p < 0.01). The corresponding value of sIL-2R beta in healthy volunteers was 605 pg/ml; in active UC, significantly lower levels were found at 233 pg/ml (p < 0.01), whereas in inactive UC, no such difference was observed at 725 pg/ml (p > 0.05). In CD, the levels were 839 pg/ml in inactive and 920 pg/ml in active disease stages (p > 0.05 vs controls). A positive and significant correlation existed between sIL-2R levels of alpha and beta chains in CD (r = 0.64; p < 0.01) but not in UC (r = -0.32; p > 0.05) or in healthy volunteers (r = 0.16; p > 0.05).

CONCLUSION: Future longitudinal studies will be necessary to learn whether this newly assessed sIL-2R beta (CD122), which may interfere with IL-15R, could be used to predict disease exacerbation and to monitor anti-inflammatory therapy in UC.