Immunological Mechanisms of Adsorptive Cytapheresis in Inflammatory Bowel Disease

Ulcerative colitis and Crohn's disease are the two main forms of inflammatory bowel disease (IBD). The study of immunological pathways involved in the onset of IBD is of fundamental importance to identify potential biological markers of disease activity and specific targets for therapy. Removing excess and activated circulating leukocytes with adsorptive cytapheresis has been shown to be a potentially effective treatment for patients with an inflamed bowel. Adsorptive cytapheresis is a non-pharmacological approach for active IBD, in which known sources of inflammatory cytokines such as activated myeloid lineage leucocytes are selectively depleted from the circulatory system. The decrease in inflammatory load caused by removing these cells is thought to enhance drug therapy and thereby promote disease remission. The benefit of cytapheresis appears to rest upon its ability to reduce levels of certain immune cell populations; however, whether this depletion results in further changes in lymphocyte populations and cytokine production needs further clarification. In this review, we aim to summarize existing evidence on the role of cytapheresis in patients with IBD, its effect on cytokine levels and cellular populations, and to discuss its potential impact on disease activity.