The production of interferon-gamma-inducible protein 10 by granulocytes and monocytes is associated with ulcerative colitis disease activity.

BACKGROUND

To clarify which types of cells produce interferon-gamma-inducible protein 10 (IP-10) and whether IP-10 is associated with the development of ulcerative colitis (UC), we investigated IP-10 production in UC patients.

METHODS

Serum IP-10 levels were measured using enzyme-linked immunosorbent assay in 29 patients with active and 21 with inactive UC and in 20 controls. The production of IP-10 by granulocytes and monocytes adsorbed to G-1 beads was examined. In 21 active UC patients treated with granulocyte and monocyte/macrophage adsorptive apheresis (GMA), serum IP-10 levels were measured before and after treatment. IP-10-positive cells in UC mucosa were also examined immunohistochemically using tissues obtained by surgical resection and colonoscopic biopsies.

RESULTS

Serum IP-10 levels in active UC patients were significantly higher than those in inactive patients, although even in the latter the levels were increased compared with those in controls. IP-10 production by granulocytes and monocytes in active UC patients was significantly higher than that in controls. Furthermore, the number of IP-10-positive cells was elevated in the colonic mucosa of patients with active UC, and one of the main subpopulations of IP-10-positive cells was granulocytes. Serum IP-10 levels decreased following GMA treatment in responders, but not in nonresponders. Interestingly, serum IP-10 levels before GMA were higher in responders than in nonresponders. In parallel with the serum levels, IP-10-positive cells also decreased following GMA treatment.

CONCLUSIONS

Serum IP-10 levels reflected UC disease activity, and the source of IP-10 was granulocytes and monocytes. Furthermore, serum IP-10 levels may be a marker for the responsiveness of patients to GMA treatment.