The possibility that IL-33 may play important roles in the response to trauma and infection is further supported by the observation that increased serum levels of a soluble form of the IL-33 receptor ST2 have been associated with numerous human diseases, including sepsis and trauma [31], acute myocardial infarction [32], chronic heart failure [33], idiopathic pulmonary fibrosis [34], asthma and allergic airway inflammation [35], rheumatoid arthritis and systemic lupus erythematosus [36]. Here, IL33 is linked to rheumatoid arthritis.