Complete heart block due to interleukin-2 therapy

Interleukin-2 (IL-2) is a naturally occurring protein which is made by white blood cells (leukocytes) and which improves the response of leukocytes to infection. IL-2 is being studied as a possible treatment for cancer, and several side effects from its use have been reported. A case is reported in which a 63-year-old woman being treated with IL-2 for kidney cancer developed dysfunction in electrical conduction in the heart. Following six treatments with IL-2, the patient developed heart arrhythmias, which developed into heart block, in which the upper and lower chambers beat independently rather in the normal coordinated fashion. The basis for the reaction is unclear, but the study suggests that heart complications of IL-2 treatment may be common, and suggest that potential candidates for IL-2 therapy should be screened for underlying heart disease. (Consumer Summary produced by Reliance Medical Information, Inc.)