Interleukin-33 Receptor (ST2)

The interleukin-33 receptor, primarily known as ST2 or IL1RL1, is a member of the interleukin-1 receptor family and serves as the main signaling receptor for the cytokine interleukin-33 (IL-33). The functional signaling complex consists of ST2 and the co-receptor IL-1 receptor accessory protein (IL-1RAcP). Upon engagement by IL-33, the ST2–IL-33–IL-1RAcP complex recruits MyD88 adaptor protein, triggering downstream activation of NF-kappa-B and MAP kinase pathways, leading to transcriptional activation of pro-inflammatory genes. The interleukin-33/ST2 axis plays key roles in initiating type 2 innate immune responses, amplifying allergic inflammation, and promoting tissue repair after injury. It acts as an “alarmin,” released upon cellular damage or necrosis, alerting the immune system during tissue stress or trauma.

Other names

IL1RL1Serum Stimulation-Inducible ProteinSTIST2L

IL-33 binding triggers MyD88-dependent activation of NF-kB and MAPK pathways.