Critical comment: analyzing the effect of novel therapies on cytokine expression in inflammatory bowel disease: do cytokine levels reflect clinical response?

Over the past several years, research in the field of cytokine production and function has become indispensable to understand the immunopathology of chronic intestinal inflammation. Thereupon, clinical studies analyzing cytokine production have generated a tremendous amount of data. In patients with inflammatory bowel disease, several studies examined pro-inflammatory cytokines in gut tissue and plasma, but a clear interpretation of the results with respect to disease activity or therapeutic response has been hampered by patient- and sample-related pitfalls.