Leukocyte adsorptive apheresis reduces less-differentiated dendritic cells (ldDC) which increased in active ulcerative colitis

Abstract

Leukocyte adsorptive apheresis (L-CAP and G-CAP) is an effective treatment for ulcerative colitis (UC). We reported that leukocyte absorption might influence blood dendritic cell subsets constitution in UC patients ¹⁾. In this study, we aimed to clarify how DC subsets change during the leukocyte adsorptive apheresis session against active UC. Twelve active UC patients were enrolled in this study. These patients received either 6 or 11 sessions of leukocyte adsorptive apheresis and 3,000mL of whole blood was evenly processed at each leukocyte absorption session. All patients received prednisolone at a dose of 30±10mg/body before leukocyte adsorptive apheresis and each dose did not change during the whole leukocyte adsorptive apheresis session. Peripheral blood samples were examined at every first, 3rd, 6th and 11th leukocyte adsorptive apheresis session. Using 4 colors FACS, total DC were captured as negative for Lineage marker (CD3, CD14, CD16, CD19, CD20 and CD56) and positive for HLA-DR. Next, total DC were divided into DC subsets as DC1, DC2 and less-differentiated DC (ldDC) by reactivity of CD11C and CD123 antibody. Above 50 points decreases by Seo activity index was evaluated as the effective group. Therapeutic effectiveness was obtained in 8 of 12 UC patients and the DC subsets were compared to those of healthy volunteers, the leukocyte adsorptive apheresis-effective group and leukocyte adsorptive apheresis-ineffective group. Total DC, DC1 and DC2 did not significantly differ between healthy volunteers and UC patients, and did not significantly change during the leukocyte adsorptive apheresis session. However, the ldDC concentration before leukocyte adsorptive apheresis was significantly higher in UC patients than in healthy volunteers (p<0.03) and significantly decreased toward the healthy control level after the final leukocyte adsorptive apheresis session in the leukocyte adsorptive apheresis-effective group. These outcomes indicate that leukocyte adsorptive apheresis reduces less-differentiated dendritic cells (ldDC), which are increased in active ulcerative colitis.