Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues. Any disease that results from such an aberrant immune response is termed an "autoimmune disease". Prominent examples include celiac disease, post-infectious IBS, diabetes mellitus type 1, Henloch Scholein Pupura (HSP) sarcoidosis, systemic lupus erythematosus (SLE), Sjögren syndrome, eosinophilic granulomatosis with polyangiitis, Hashimoto's thyroiditis, Graves' disease, idiopathic thrombocytopenic purpura, Addison's disease, rheumatoid arthritis (RA), ankylosing spondylitis, polymyositis (PM), dermatomyositis (DM) and multiple sclerosis (MS). Autoimmune diseases are very often treated with steroids.
Antiphospholipid syndrome, or antiphospholipid antibody syndrome, is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS provokes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, and severe preeclampsia. The diagnostic criteria require one clinical event and two positive blood test results spaced at least three months apart that detect lupus anticoagulant, anti-apolipoprotein antibodies, or anti-cardiolipin antibodies.
Thrombin is a serine protease, an enzyme that, in humans, is encoded by the F2 gene. Prothrombin is proteolytically cleaved to form thrombin in the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions.
Antinuclear antibodies are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human proteins (autoantigens). In some individuals, antibodies to human antigens are produced.
Antithrombin (AT) is a small protein molecule that inactivates several enzymes of the coagulation system. Antithrombin is a glycoprotein produced by the liver and consists of 432 amino acids. It contains three disulfide bonds and a total of four possible glycosylation sites. α-Antithrombin is the dominant form of antithrombin found in blood plasma and has an oligosaccharide occupying each of its four glycosylation sites. A single glycosylation site remains consistently un-occupied in the minor form of antithrombin, β-antithrombin. Its activity is increased manyfold by the anticoagulant drug heparin, which enhances the binding of antithrombin to factor IIa (Thrombin) and factor Xa.
The classical complement pathway is one of three pathways which activate the complement system, which is part of the immune system. The classical complement pathway is initiated by antigen-antibody complexes with the antibody isotypes IgG and IgM.
Lupus anticoagulant is an immunoglobulin that binds to phospholipids and proteins associated with the cell membrane. Its name is a misnomer, as it is actually a prothrombotic antibody. Lupus anticoagulant in living systems cause an increase in inappropriate blood clotting. The name derives from their properties in vitro, as these antibodies increase laboratory coagulation tests such as the aPTT. Investigators speculate that the antibodies interfere with phospholipids used to induce in vitro coagulation. In vivo, the antibodies are thought to interact with platelet membrane phospholipids, increasing adhesion and aggregation of platelets, which accounts for the in vivo prothrombotic characteristics.
An autoantibody is an antibody produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases are caused by such autoantibodies.
Anti-mitochondrial antibodies (AMA) are autoantibodies, consisting of immunoglobulins formed against mitochondria, primarily the mitochondria in cells of the liver.
Extractable Nuclear Antigens (ENAs) are over 100 different soluble cytoplasmic and nuclear antigens. They are known as “extractable” because they can be removed from cell nuclei using saline and represent six main proteins: Ro, La, Sm, RNP, Scl-70, Jo1. Most ENAs are part of spliceosomes or nucleosomes complexes and are a type of small nuclear ribonucleoprotein (snRNPS). The location in the nucleus and association with spliceosomes or nucleosomes results in these ENAs being associated with additional RNA and proteins such as polymerases. This quality of ENAs often makes it difficult to purify and quantify their presence for clinical use.
Belimumab, sold under the brand name Benlysta, is a human monoclonal antibody that inhibits B-cell activating factor (BAFF), also known as B-lymphocyte stimulator (BLyS). It is approved in the United States, Canada, and Europe to treat systemic lupus erythematosus (SLE).
β2-glycoprotein 1, also known as beta-2 glycoprotein 1 and Apolipoprotein H (Apo-H), is a 38 kDa multifunctional plasma protein that in humans is encoded by the APOH gene. One of its functions is to bind cardiolipin. When bound, the structure of cardiolipin and β2-GP1 both undergo large changes in structure. Within the structure of Apo-H is a stretch of positively charged amino acids, Lys-Asn-Lys-Glu-Lys-Lys, are involved in phospholipid binding.
Anti-cardiolipin antibodies (ACA) are antibodies often directed against cardiolipin and found in several diseases, including syphilis, antiphospholipid syndrome, livedoid vasculitis, vertebrobasilar insufficiency, Behçet's syndrome, idiopathic spontaneous abortion, and systemic lupus erythematosus (SLE). They are a form of anti-mitochondrial antibody. In SLE, anti-DNA antibodies and anti-cardiolipin antibodies may be present individually or together; the two types of antibodies act independently. This is in contrast to rheumatoid arthritis with systemic sclerosis (scleroderma) because anti-cardiolipin antibodies are present in both conditions, and therefore may tie the two conditions together.
Anti-topoisomerase antibodies (ATA) are autoantibodies directed against topoisomerase and found in several diseases, most importantly scleroderma. Diseases with ATA are autoimmune disease because they react with self-proteins. They are also referred to as anti-DNA topoisomerase I antibody.
In autoimmune disease, anti-apolipoprotein H (AAHA) antibodies, also called anti-β2 glycoprotein I antibodies, comprise a subset of anti-cardiolipin antibodies and lupus anticoagulant. These antibodies are involved in sclerosis and are strongly associated with thrombotic forms of lupus. As a result AAHA are strongly implicated in autoimmune deep vein thrombosis.
Interferon alpha-1/13 is a protein that in humans is encoded by the IFNA1 gene.
Anti-double stranded DNA (Anti-dsDNA) antibodies are a group of anti-nuclear antibodies (ANA) the target antigen of which is double stranded DNA. Blood tests such as enzyme-linked immunosorbent assay (ELISA) and immunofluorescence are routinely performed to detect anti-dsDNA antibodies in diagnostic laboratories. They are highly diagnostic of systemic lupus erythematosus (SLE) and are implicated in the pathogenesis of lupus nephritis.
Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary between people and may be mild to severe. Common symptoms include painful and swollen joints, fever, chest pain, hair loss, mouth ulcers, swollen lymph nodes, feeling tired, and a red rash which is most commonly on the face. Often there are periods of illness, called flares, and periods of remission during which there are few symptoms.
Anti-histone antibodies are autoantibodies that are a subset of the anti-nuclear antibody family, which specifically target histone protein subunits or histone complexes. They were first reported by Henry Kunkel, H.R. Holman, and H.R.G. Dreicher in their studies of cellular causes of lupus erythematosus in 1959–60. Today, anti-histone antibodies are still used as a marker for systemic lupus erythematosus, but are also implicated in other autoimmune diseases like Sjogren's Syndrome, dermatomyositis, or rheumatoid arthritis. Anti-histone antibodies can be used as a marker for drug-induced lupus.
Anti-SSA autoantibodies are a type of anti-nuclear autoantibodies that are associated with many autoimmune diseases, such as systemic lupus erythematosus (SLE), SS/SLE overlap syndrome, subacute cutaneous lupus erythematosus (SCLE), neonatal lupus and primary biliary cirrhosis. They are often present in Sjögren's syndrome (SS). Additionally, Anti-Ro/SSA can be found in other autoimmune diseases such as systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), rheumatoid arthritis (RA), and mixed connective tissue disease (MCTD), and are also associated with heart arrhythmia.
