ST2 is a member of the interleukin 1 receptor family. The ST2 protein has two isoforms and is directly implicated in the progression of cardiac disease: the soluble form (referred to as soluble ST2 or sST2) and the membrane-bound receptor form (referred to as the ST2 receptor or ST2L).

IL-33 has been identified as a ligand for ST2 and IL-33/ST2 signaling is involved in T-cell mediated immune responses implicated in a number of inflammatory conditions including asthma, fibroproliferative diseases, autoimmune diseases, sepsis, and malignancy. Binding of IL-33 to the ST2 receptor, in response to cardiac disease or injury, such as an ischemic event, elicits a cardio protective effect resulting in preserved cardiac function.

In individuals with acute myocardial infarction (AMI), an increased concentration of soluble ST2 is associated with an increased risk of heart failure (HF). Among all the cardiac biomarkers, ST2 also appears to be minimally affected by patient characteristics such as age, obesity, etiology of HF, and anemia among other. The low-biological variability of sST2 makes it an ideal biomarker for serial measurements to monitor disease course and response to therapy.