Inhibits the activity of interleukin-36 (IL36A,IL36B and IL36G) by binding to receptor IL1RL2 and preventing its association with the coreceptor IL1RAP for signaling. Part of the IL-36 signaling system that is thought to be present in epithelial barriers and to take part in local inflammatory response; similar to the IL-1 system with which it shares the coreceptor. Proposed to play a role in skin inflammation. May be involved in the innate immune response to fungal pathogens, such as Aspergillus fumigatus. May activate an anti- inflammatory signaling pathway by recruiting SIGIRR. {ECO:0000269|PubMed:11466363, ECO:0000269|PubMed:21965679, ECO:0000269|PubMed:23147407}. This is the function of ENSG00000136695 (IL36RN, interleukin 36 receptor antagonist).