The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as CD ) is a protocol used for the identification and investigation of cell surface molecules providing targets for immunophenotyping of cells. In terms of physiology, CD molecules can act in numerous ways, often acting as receptors or ligands important to the cell. A signal cascade is usually initiated, altering the behavior of the cell (see cell signaling ). Some CD proteins do not play a role in cell signaling, but have other functions, such as cell adhesion . CD for humans is numbered up to 371 (as of 21 April 2016 ).
14-1125: 1J2E , 1N1M , 1NU6 , 1NU8 , 1PFQ , 1R9M , 1R9N , 1RWQ , 1TK3 , 1TKR , 1U8E , 1W1I , 1WCY , 1X70 , 2AJL , 2BGN , 2BGR , 2BUB , 2FJP , 2G5P , 2G5T , 2G63 , 2HHA , 2I03 , 2I78 , 2IIT , 2IIV , 2JID , 2OAG , 2OGZ , 2OLE , 2ONC , 2OPH , 2OQI , 2OQV , 2P8S , 2QJR , 2QKY , 2QOE , 2QT9 , 2QTB , 2RGU , 2RIP , 3BJM , 3C43 , 3C45 , 3CCB , 3CCC , 3D4L , 3EIO , 3F8S , 3G0B , 3G0C , 3G0D , 3G0G , 3H0C , 3HAB , 3HAC , 3KWF , 3KWJ , 3NOX , 3O95 , 3O9V , 3OC0 , 3OPM , 3Q0T , 3Q8W , 3QBJ , 3SWW , 3SX4 , 3VJK , 3VJL , 3VJM , 3W2T , 4A5S , 4DSA , 4DSZ , 4DTC , 4G1F , 4JH0 , 4KR0 , 4L72 , 4LKO , 4J3J , 4N8D , 4N8E , 4PNZ , 4PV7 , 4QZV , 3WQH , 5KBY , 5ISM , 5I7U 1803 13482 ENSG00000197635 ENSMUSG00000035000 P27487 P28843 NM_001935 NM_001159543 NM_010074 NP_001926 NP_001366533 NP_001366534 NP_001366535 NP_001153015 NP_034204 Dipeptidyl peptidase-4 ( DPP4 or DPPIV ), also known as adenosine deaminase complexing protein 2 or CD26 ( cluster of differentiation 26)
28-410: A chemokine receptor on the surface of a T helper cell to gain entry. The number of CD4 and CD8 T cells in blood is often used to monitor the progression of HIV infection . While CD molecules are very useful in defining leukocytes, they are not merely markers on the cell surface . Though only a fraction of known CD molecules have been thoroughly characterised, most of them have important functions. In
42-471: A " CD34 +, CD31 −" cell is one that expresses CD34 but not CD31. This CD combination typically corresponds to a stem cell , as opposed to a fully differentiated endothelial cell . Some cell populations can also be defined as , , or (alternatively, , , or ), indicating an overall variability in CD expression , particularly when compared to other cells being studied. A review of the development of T cells in
56-525: A major role in glucose metabolism. It is responsible for the degradation of incretins such as GLP-1 . Furthermore, it appears to work as a suppressor in the development of some tumors . DPP-4 also binds the enzyme adenosine deaminase specifically and with high affinity. The significance of this interaction has yet to be established. Animal studies suggest its pathogenetic role in development of fibrosis of various organs, such as liver and kidney. CD26/DPPIV plays an important role in tumor biology, and
70-497: Is a protein that, in humans, is encoded by the DPP4 gene . DPP4 is related to FAP , DPP8 , and DPP9 . The enzyme was discovered in 1966 by Hopsu-Havu and Glenner, and as a result of various studies on chemism, was called dipeptidyl peptidase IV [DP IV]. The protein encoded by the DPP4 gene is an enzyme expressed on the surface of most cell types and is associated with immune regulation, signal transduction , and apoptosis . It
84-588: Is a type II transmembrane glycoprotein , but a soluble form, which lacks the intracellular and transmembrane part, is present in blood plasma and various body fluids. DPP-4 is a serine exopeptidase that cleaves X-proline or X-alanine dipeptides from the N-terminus of polypeptides . Peptide bonds involving the cyclic amino acid proline cannot be cleaved by the majority of proteases and an N-terminal X-proline "shields" various biopeptides. Extracellular proline-specific proteases therefore play an important role in
98-400: Is assigned a CD number once two specific monoclonal antibodies are shown to bind to the molecule. If the molecule has not been well characterized or has only one mAb, it is usually given the provisional indicator "w" (as in " CDw186 "). For instance, CD2 mAbs are reagents that react with a 50‐kDa transmembrane glycoprotein expressed on T cells . The CD designations were used to describe
112-417: Is found on the surface of cells in the airways (such as the lungs) and kidneys. Scientists may be able to use this to their advantage by blocking the virus's entry into the cell. DPP4, or its Mycobacterial homologue MtDPP, might play a role in the pathogenesis of tuberculosis via cleavage of the chemokine C-X-C motif chemokine ligand 10 ( CXCL10 ). Cluster of differentiation The CD nomenclature
126-635: Is uncommon (though a few examples exist), combining markers has allowed for cell types with very specific definitions within the immune system. CD molecules are utilized in cell sorting using various methods, including flow cytometry . Two commonly used CD molecules are CD4 and CD8 , which are, in general, used as markers for helper and cytotoxic T cells, respectively. These molecules are defined in combination with CD3+, as some other leukocytes also express these CD molecules (some macrophages express low levels of CD4; dendritic cells express high levels of CD8). Human immunodeficiency virus binds CD4 and
140-413: Is useful as a marker for various cancers, with its levels either on the cell surface or in the serum increased in some neoplasms and decreased in others. A class of oral hypoglycemics called dipeptidyl peptidase-4 inhibitors works by inhibiting the action of this enzyme, thereby prolonging incretin effect in vivo . Middle East respiratory syndrome coronavirus has been found to bind to DPP4. It
154-519: The thymus uses this nomenclature to identify cells transitioning from CD4 /CD8 double-positive cells to CD4 /CD8 . Since 1982 there have been nine Human Leukocyte Differentiation Antigen Workshops culminating in a conference. The CD system is commonly used as cell markers in immunophenotyping , allowing cells to be defined based on what molecules are present on their surface. These markers are often used to associate cells with certain immune functions . While using one CD molecule to define populations
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#1732783896072168-408: The recognized molecules but had to be clarified by attaching the term antigen or molecule to the designation (e.g., CD2 molecule). Currently, "CD2" is generally used to designate the molecule, and "CD2 antibody " is used to designate the antibody. Cell populations are usually defined using a '+' or a '−' symbol to indicate whether a certain cell fraction expresses or lacks a CD molecule. For example,
182-406: The regulation of these biopeptides. DPP-4 is known to cleave a broad range of substrates including growth factors , chemokines , neuropeptides , and vasoactive peptides. The cleaved substrates lose their biological activity in the majority of cases, but in the case of the chemokine RANTES and neuropeptide Y, DPP-4 mediated cleavage leads to a shift in the receptor subtype binding. DPP4 plays
196-600: Was proposed and established in the 1st International Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Paris in 1982. This system was intended for the classification of the many monoclonal antibodies (mAbs) generated by different laboratories around the world against epitopes on the surface molecules of leukocytes (white blood cells). Since then, its use has expanded to many other cell types, and more than 370 CD unique clusters and subclusters have been identified. The proposed surface molecule
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