Biological Activity: Fully biologically active when compared to standard. The ED50 as determined by inducing IL-8 secretion in human preadipocytes is less than 10 ng/mL, corresponding to a specific activity of > 1.0 x 105 IU/mg.
Relevance: Cytokine that binds to and signals through the IL1RL2/IL-36R receptor which in turn activates NF-kappa-B and MAPK signaling pathways in target cells linked to a pro-inflammatory response. 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 IL1RAP. Seems to be involved in skin inflammatory response by acting on keratinocytes, dendritic cells and indirectly on T cells to drive tissue infiltration, cell maturation and cell proliferation. In cultured keratinocytes induces the expression of macrophage, T cell, and neutrophil chemokines, such as CCL3, CCL4, CCL5, CCL2, CCL17, CCL22, CL20, CCL5, CCL2, CCL17, CCL22, CXCL8, CCL20 and CXCL1, and the production of proinflammatory cytokines such as TNF-alpha, IL-8 and IL-6. In cultured monocytes upregulates expression of IL-1A, IL-1B and IL-6. In myeloid dendritic cells involved in cell maturation by upregulating surface expression of CD83, CD86 and HLA-DR. In monocyte-derived dendritic cells facilitates dendritic cell maturation and drives T cell proliferation. May play a role in proinflammatory effects in the lung. {ECO:0000269|PubMed:14734551, ECO:0000269|PubMed:21881584, ECO:0000269|PubMed:21965679, ECO:0000269|PubMed:24829417}. Synonyms: FIL1 epsilon, IL-1 epsilon, Interleukin-1 family member 6, IL-1F6,