IL1B and rheumatoid arthritis: IL-1Ra is found in the bloodstream of healthy subjects at a concentration ranging from 100 to 300 ng/mL, and is a natural molecule of the IL-1 family, most currently used for the treatment of rheumatoid arthritis, but has also been shown to be effective in a broad spectrum of inflammatory states, including heart disease and some autoimmune diseases, as well as having been identified as a candidate stroke drug [61,62].