Inhibitory receptor acting as a major negative regulator of T-cell responses (PubMed:11279501, PubMed:11279502, PubMed:16551244, PubMed:1714933, PubMed:18641304, PubMed:28484017). Acts as a decoy receptor: the affinity of CTLA4 for its natural B7 family ligands, CD80 and CD86, is considerably stronger than the affinity of their cognate stimulatory coreceptor CD28 (PubMed:11279501, PubMed:11279502, PubMed:16551244, PubMed:1714933, PubMed:28484017)

Homodimer; disulfide-linked (PubMed:11279501, PubMed:11279502, PubMed:21156796, PubMed:28484017, Ref.24). Interacts with ICOSLG (PubMed:28484017)

Widely expressed with highest levels in lymphoid tissues. Detected in activated T-cells where expression levels are 30- to 50-fold less than CD28, the stimulatory coreceptor, on the cell surface following activation

• Systemic lupus erythematosus (SLE)

  A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow.

• Unknown disease
• Type 1 diabetes mellitus 12 (T1D12)

  A multifactorial disorder of glucose homeostasis that is characterized by susceptibility to ketoacidosis in the absence of insulin therapy. Clinical features are polydipsia, polyphagia and polyuria which result from hyperglycemia-induced osmotic diuresis and secondary thirst. These derangements result in long-term complications that affect the eyes, kidneys, nerves, and blood vessels.

• Celiac disease 3 (CELIAC3)

  A multifactorial, chronic disorder of the small intestine caused by intolerance to gluten. It is characterized by immune-mediated enteropathy associated with failed intestinal absorption, and malnutrition. In predisposed individuals, the ingestion of gluten-containing food such as wheat and rye induces a flat jejunal mucosa with infiltration of lymphocytes.

• Immune dysregulation with autoimmunity, immunodeficiency, and lymphoproliferation (IDAIL)

  An autosomal dominant primary immunodeficiency characterized by severe autoimmunity, infiltration of non-lymphoid organs, such as the intestine, lungs and brain, by hyperactive T cells and B cells, autoimmune cytopenias, and hypogammaglobulinemia in early childhood.