Cluster of differentiation
Cluster of differentiation (CD) molecules are markers on the cell surface, as recognized by specific sets of antibodies, used to identify the cell type, stage of differentiationand activity of a cell.
- 1 Nomenclature
- 2 Uses
- 3 See also
- 4 External links
The CD nomenclature was proposed and established in the 1st International Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), which was held in Parisin 1982. This system was intended for the classification of the many monoclonal antibodies(mAbs), generated by different laboratories around the world, against various surface molecules (antigens) on leukocytes (white blood cells). Since then, the use has expanded to many other cell types, and more than 250 CD clusters and subclusters have been identified. The HLDA workshops assign each CD based on the same reactivity to one human antigen by at least two mAbs; the provisional indicator "w" (as in "CDw186") is sometimes given to a cluster not well characterized or represented by only one mAb.
- CD molecules are often referred to when sorting cells by flow cytometry. A '+' or a '–' symbol is used to indicate if a certain fraction of cells possesses or lacks a CD molecule; for example, a "CD34+, CD31–" cell is one that expresses CD34, but not CD31.
- The most commonly referred to CD molecules are CD4 and CD8, which are markers for two different subtypes of T-lymphocytes, for the most part (Dendritic cellsalso express CD8). CD4 is specifically recognized and bound by HIV, leading to viral infection and destruction of CD4+ T cells. The relative abundance of CD4+ and CD8+ T cells is often used to monitor the progression of an HIVinfection.
- CD molecules are not merely markers on the cell surface. Not every CD molecule has been thoroughly characterised, but most of them bring important features to the cells that carry them. In the example of CD4 & CD8, these molecules are critical in the antigen recognition pathway.
- List of human clusters of differentiationfor a list of CD molecules
- A list of CD molecules, at ebioscience.com
- Another list of CD molecules, at Expasy.org
- Yet another list of CD molecules, at PathologyOutlines.com
- Catalogue of some CD-factors, as R&D Systems.cs:Diferencia?ní skupina
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Categories: Anatomical pathology| Immunology| Clusters of differentiation
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It uses material from the http://en.wikipedia.org/wiki/Cluster+of+differentiation Wikipedia article Cluster of differentiation.