IL-1R1 also known as IL1Ralpha, IL1RA, CD121A is a cytokine receptor that belongs to the interleukin-1 receptor family. IL-1R1 plays a crucial role in mediating the effects of interleukin-1, a key cytokine involved in inflammatory responses. IL-1R1 is primarily located on the surface of various immune and non-immune cells, including macrophages and fibroblasts, which is significant because IL-1R1 expression is essential for the initiation of pro-inflammatory signaling pathways. Upon binding with IL-1α and IL-1β ligands, IL-1R1 activates intracellular signaling cascades that lead to the production of additional inflammatory mediators, thus amplifying the immune response.