Leukocyte Removal Filter‐Passed Lymphocytes Produce Large Amounts of Interleukin‐4 in Immunotherapy for Inflammatory Bowel Disease: Role of Bystander Suppression

Abstract

To determine immunosuppression by leukocytapheresis, we studied the immune profiles of filter-passed lymphocytes (FPLs) in patients with ulcerative colitis. These patients were treated with a leukocytapheresis (LCAP) filter of granulocyte apheresis (GCAP) column. Cytokine profiles or FPLs and peripheral blood mononuclear cells (PBMCs) were examined using interleukin (IL)-4 and interferon-gamma (IFN-gamma) immunoassay with lectin stimulation. The IL-4 production of LCAP FPLs was significantly higher than in prefilter PBMCs and GCAP column-passed lymphocytes (median: 540 pg/ml x 10(6) cells versus 4.7 and 2.9, respectively, p = 0.001). IL-4 production in PBMCs was increased after LCAP. IFN-gamma production was not increased in the FPLs. The IL-4 immune deviation was not shown in the patients treated with GCAP. LCAP FPLs showed increased CD4+DR- cells and decreases CD4+DR+ cells in comparison to PBMCs. LCAP FPLs could produce IL-4 and may lead to bystander suppression.