Systemic interleukin-6 response to colorectal surgery originates from the bowel

Background. Surgical trauma evokes a systemic cytokine response which is enhanced in patients with colorectal cancer. The aim of this study was to locate the origin of the systemic cytokine response to colorectal surgery. Methods: The concentrations of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) were analysed in systemic and mesenteric venous blood in 12 patients operated on with colorectal resections due to cancer or benign lesions. Immunohistochemical staining and analysis of tissue concentrations of IL-6 and TNF-alpha in homogenates from tumours and benign specimens were performed. Results: Mesenteric venous blood contained higher concentrations of IL-6 compared to systemic venous blood after resection, but not before. Tissue concentration of IL-6 was higher in the tumours compared to the benign specimens and immunohistochemistry revealed an abundance of IL-6 and TNF-alpha in malignant epithelium compared to benign mucosa. Conclusion: The higher concentration of IL-6 in venous blood from the mesenterium of the resected colonic segment compared to systemic levels, indicates that the bowel is the source of the IL-6 response to surgical trauma in colorectal surgery. Copyright (C) 2002 S. Karger AG, Basel.