Interleukin-6 is one of the most well-characterized cytokines with pleiotropic properties. Besides its B-lymphocyte activation role in hematopoiesis, interleukin-6 plays a central role in regulation of systemic inflammation. Interleukin-6 binds to receptors on target cells (such as hepatocytes and lymphocytes), consisting of an 80 kDa binding chain and gp130, a polypeptide responsible for signal transduction. In addition to the detection of elevated amounts of interleukin-6 in the blood, gene expression (mRNA) of subunits of the interleukin-6 receptor complex have also been studied by examining the reverse transcriptase polymerase chain reaction on peripheral lymphocytes from patients with characteristic radiological symptoms suffering from Crohn's disease. Our data show significantly elevated gene expression both of the 80 kDa interleukin-6 binding chain and gp130. These results suggest that enhancement of the expression of the constituents of interleukin-6 and the interleukin-6 receptor system plays a relevant role in systemic inflammation in inflammatory bowel disease.