Test Details: Interleukin-6 (IL-6) is a protein produced by various cells and is one of the large group of molecules called cytokines. It helps regulate immune responses which makes the IL-6 test potentially useful as a marker of immune system activation. IL-6 can be elevated with inflammation, infection, autoimmune disorders, cardiovascular diseases and some cancers. This test measures the amount of IL-6 in the blood and helps to monitor inflammatory responses.