In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". Prominent examples include celiac disease, post-infectious IBS, diabetes mellitus type 1, Henoch–Schönlein purpura (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.
CTLA-4 or CTLA4, also known as CD152, is a protein receptor that functions as an immune checkpoint and downregulates immune responses. CTLA-4 is constitutively expressed in regulatory T cells but only upregulated in conventional T cells after activation – a phenomenon which is particularly notable in cancers. It acts as an "off" switch when bound to CD80 or CD86 on the surface of antigen-presenting cells.
B-lymphocyte antigen CD20 or CD20 is expressed on the surface of all B-cells beginning at the pro-B phase and progressively increasing in concentration until maturity.
HLA-DQ (DQ) is a cell surface receptor protein found on antigen-presenting cells. It is an αβ heterodimer of type MHC class II. The α and β chains are encoded by two loci, HLA-DQA1 and HLA-DQB1, that are adjacent to each other on chromosome band 6p21.3. Both α-chain and β-chain vary greatly. A person often produces two α-chain and two β-chain variants and thus 4 isoforms of DQ. The DQ loci are in close genetic linkage to HLA-DR, and less closely linked to HLA-DP, HLA-A, HLA-B and HLA-C.
Self-protein refers to all proteins endogenously produced by DNA-level transcription and translation within an organism of interest. This does not include proteins synthesized due to viral infection, but may include those synthesized by commensal bacteria within the intestines. Proteins that are not created within the body of the organism of interest, but nevertheless enter through the bloodstream, a breach in the skin, or a mucous membrane, may be designated as “non-self” and subsequently targeted and attacked by the immune system. Tolerance to self-protein is crucial for overall wellbeing; when the body erroneously identifies self-proteins as “non-self”, the subsequent immune response against endogenous proteins may lead to the development of an autoimmune disease.
Chromogranin A or parathyroid secretory protein 1 is a member of the granin family of neuroendocrine secretory proteins. As such, it is located in secretory vesicles of neurons and endocrine cells such as islet beta cell secretory granules in the pancreas. In humans, chromogranin A protein is encoded by the CHGA gene.
Anti-transglutaminase antibodies (ATA) are autoantibodies against the transglutaminase protein. Antibodies serve an important role in the immune system by detecting cells and substances that the rest of the immune system then eliminates. These cells and substances can be foreign and also can be produced by the body. Antibodies against the body's own products are called autoantibodies. Autoantibodies can sometimes errantly be directed against healthy portions of the organism, causing autoimmune diseases.
HLA-DQ2 (DQ2) is a serotype group within HLA-DQ (DQ) serotyping system. The serotype is determined by the antibody recognition of β2 subset of DQ β-chains. The β-chain of DQ is encoded by HLA-DQB1 locus and DQ2 are encoded by the HLA-DQB1*02 allele group. This group currently contains two common alleles, DQB1*0201 and DQB1*0202. HLA-DQ2 and HLA-DQB1*02 are almost synonymous in meaning. DQ2 β-chains combine with α-chains, encoded by genetically linked HLA-DQA1 alleles, to form the cis-haplotype isoforms. These isoforms, nicknamed DQ2.2 and DQ2.5, are also encoded by the DQA1*0201 and DQA1*0501 genes, respectively.
Major histocompatibility complex, class II, DQ beta 1, also known as HLA-DQB1, is a human gene and also denotes the genetic locus that contains this gene. The protein encoded by this gene is one of two proteins that are required to form the DQ heterodimer, a cell surface receptor essential to the function of the immune system.
Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is a cytoplasmatic protein encoded by gene PTPN22 and a member of PEST family of protein tyrosine phosphatases. This protein is also called "PEST-domain Enriched Phosphatase" ("PEP") or "Lymphoid phosphatase" ("LYP"). The name LYP is used strictly for the human protein encoded by PTPN22, but the name PEP is used only for its mouse homolog. However, both proteins have similar biological functions and show 70% identity in amino acid sequence. PTPN22 functions as a negative regulator of T cell receptor (TCR) signaling, which maintains homeostasis of T cell compartment.
Tripartite motif-containing protein 21, also known as E3 ubiquitin-protein ligase TRIM21, is a protein that in humans is encoded by the TRIM21 gene. Alternatively spliced transcript variants for this gene have been described but the full-length nature of only one has been determined. It is expressed in most human tissues.
Receptor-type tyrosine-protein phosphatase-like N, also called "IA-2", is an enzyme that in humans is encoded by the PTPRN gene.
60 kDa SS-A/Ro ribonucleoprotein is a protein that in humans is encoded by the TROVE2 gene.
Large proline-rich protein BAT2 is a protein that in humans is encoded by the BAT2 gene.
Transcription factor SOX-13 is a protein that in humans is encoded by the SOX13 gene.
Receptor-type tyrosine-protein phosphatase N2 (R-PTP-N2) also known as islet cell autoantigen-related protein (ICAAR) and phogrin is an enzyme that in humans is encoded by the PTPRN2 gene. PTPRN and PTPRN2 are both found to be major autoantigens associated with insulin-dependent diabetes mellitus.
Cerebellar degeneration-related protein 2 is a protein that in humans is encoded by the CDR2 gene.
RNA-binding protein Raly is a protein that in humans is encoded by the RALY gene.
Glucose-6-phosphatase 2 is an enzyme that in humans is encoded by the G6PC2 gene.
Interleukin-2 receptor alpha chain is a protein involved in assembly of high-affinity Interleukin-2 receptor, consisting of alpha (IL2RA), beta (IL2RB) and the common gamma chain (IL2RG). As the name indicates, this receptor interacts with pleiotropic cytokine called Interleukin-2, which effect is mainly important for immune homeostasis.
