In summary, the available data on the involvement of IL1RL1 and its ligand IL33 in immune and autoimmune disorders are reasonably consistent; a clearer understanding of the balance between IL1RL1 isoform A/IL33, IL1RL1 isoform B/IL33 and its regulation is needed in order to make that axis a more attractive target for therapeutic intervention. Here, IL33 is linked to autoimmune disease.