Development of Crohn's disease in a patient taking etanercept.

In addition to its well known proinflammatory effects, tumor necrosis factor-alpha (TNF-a) has complex effects on the growth, differentiation, and death of immune cells. TNF antagonists have had dramatic effects on the suppression of rheumatoid arthritis and other rheumatic inflammatory diseases. However, TNF inhibition of RA has led to an increased incidence of drug induced anti-dsDNA production, with cases of systemic lupus erythematosus as well as exacerbations of multiple sclerosis. While etanercept does not generally alter the course of Crohn's disease we describe a rare instance where this agent may have contributed to the development of clinically significant inflammatory bowel disease.