Circulating Soluble Interleukin-2 Receptor α and β Chain in Inflammatory Bowel Disease

Objectives : Inflammatory bowel disease is characterized by T cell activation. Activated T cells shed interleu-kin-2 receptors (IL-2R) in a soluble form. A positive correlation between sIL-2Rα (CD25) and disease activity in inflammatory bowel disease has been shown previously, whereas IL-2Rβ (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-2Rα and -β chains were assessed by a sandwich ELISA technique using monoclonal antibodies specific for CD25 and CD122, respectively. Results : The median concentration of sIL-2Rα 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-2Rβ 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 α and β 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-2Rβ (CD122), which may interfere with IL-15R, could be used to predict disease exacerbation and to monitor anti-inflammatory therapy in UC.