Clinical Response Is Associated with Elevated Plasma Interleukin-1 Receptor Antagonist During Selective Granulocyte and Monocyte Apheresis in Patients with Ulcerative Colitis

Depletion of granulocytes and monocytes (GM) by selective apheresis (GMA) with an Adacolumn exerts an anti-inflammatory effect in patients with ulcerative colitis (UC) or rheumatoid arthritis. However, the mechanism of the anti-inflammatory effect of GMA is not fully understood yet. We investigated the effect of GMA on the plasma concentration of interleukin-1 receptor antagonist (IL-1ra), a potent anti-inflammatory cytokine. Twenty-six patients with active UC received GMA at one session per week for 5 consecutive weeks. Clinical response was defined as Δclinical activity index (ΔCAI=CAI at entry – CAI at post)≥4, while clinical remission was defined as CAI≤4. Twenty-one of twenty-six patients (80.8%) responded to GMA. In the first session, plasma from responder patients showed a significant ( P < 0.01) increase in IL-1ra in the Adacolumn outflow. In contrast, there was no change in IL-1ra in nonresponders. In conclusion, release of IL-1ra during GMA might be one mechanism of clinical efficacy associated with this therapy.