Relevance of the processed blood volume per granulocyte and monocyte apheresis session to its clinical efficacy in patients with ulcerative colitis

Granulocyte/monocyte adsorption (GMA) has been introduced as an adjunct intervention for active ulcerative colitis (UC) patients. The processed blood volume (PV) per GMA session is an important factor for its efficacy because depletion of elevated/activated myeloid leukocytes is its main action. Hitherto, this aspect of GMA has been largely ignored. Thirty-three patients were enrolled for remission induction therapy with five weekly GMA sessions at a standard PV of 1800 mL, regardless of patients' bodyweight (BW). The patients were divided into three groups: high (H)BW (≥ 65 kg, n = 11), 50 kg ≤ medium (M)BW < 65 kg (n = 12), and low (L)BW (≤ 50 kg, n = 10). UC clinical activity index (CAI) was according to Lichtiger, and the clinical efficacies were evaluated at both one week post 3(rd) GMA (Week 4) and one week post 5(th) GMA (Week 6). The average BW was 70.9 ± 6.2 kg in HBW, 55.8 ± 4.5 kg in MBW, and 46.8 ± 1.2 kg in LBW, indicating the mean PV/BW in the three groups being 25.6 ± 2.12, 32.5 ± 2.50, and 38.7 ± 1.0 (mL/kg, P < 0.05), respectively. The LBW group consisted of female patients only. Significant improvements of CAI were seen before treatment at either Week 4 or Week 6 in all groups. A significantly higher remission rate was achieved in the LBW (80.0%) vs. MBW (33.3%) or HBW (27.3%) at Week 6 (P < 0.03). According to this GMA evaluation, the lower-limit of optimum PV/kg should be higher than 38.7 mL/kg for its potential clinical efficacy to be significantly greater than the routine GMA method. Additional BW-oriented GMA studies in larger and gender controlled cohorts of patients should strengthen our findings.