Function Inhibits the activity of interleukin-1 by binding to receptor IL1R1 and preventing its association with the coreceptor IL1RAP for signaling. Has no interleukin-1 like activity. Binds functional interleukin-1 receptor IL1R1 with greater affinity than decoy receptor IL1R2; however, the physiological relevance of the latter association is unsure. Tissue specificity The intracellular form of IL1RN is predominantly expressed in epithelial cells. Involvement in disease Genetic variation in IL1RN is associated with susceptibility to microvascular complications of diabetes type 4 (MVCD4) [MIM:612628]. These are pathological conditions that develop in numerous tissues and organs as a consequence of diabetes mellitus. They include diabetic retinopathy, diabetic nephropathy leading to end-stage renal disease, and diabetic neuropathy. Diabetic retinopathy remains the major cause of new-onset blindness among diabetic adults. It is characterized by vascular permeability and increased tissue ischemia and angiogenesis. Defects in IL1RN are the cause of interleukin 1 receptor antagonist deficiency (DIRA) [MIM:612852]; also known as deficiency of interleukin 1 receptor antagonist. Autoinflammatory diseases manifest inflammation without evidence of infection, high-titer autoantibodies, or autoreactive T-cells. DIRA is a rare, autosomal recessive, genetic autoinflammatory disease that results in sterile multifocal osteomyelitis (bone inflammation in multiple places), periostitis (inflammation of the membrane surrounding the bones), and pustulosis (due to skin inflammation) from birth. Pharmaceutical use Available under the name Kineret (Amgen). Used for the reduction in signs and symptoms and slowing the progression of structural damage in moderately to severely active rheumatoid arthritis.

Cytoplasmic (isoforms 2, 3 and 4)and Secreted (isoform 1)