Clusters of differentiation (CD) are cell surface antigens. These proteins have not been gathered in this classification or protocol given their activities or functions. They have been classified as CD during an international workshop to settle a homogeneous naming system for the antigens studied all over the world. These proteins are given an arbitrary number. At the origin, CD proteins were specific to leucocytes. The classification now comprises all cell types. They can be used as identifiers of cell phenotypes. Indeed many CD proteins are specific for one cell type. However one cell type often has several associated CDs. Cells can be identified as bearing such CD or not (plus or minus sign), or expressing it more or less (high or low expression). Thus CD34 and CD117 presence while CD31 absence identify a studied cell as a stem cell. Therefore this protocol includes proteins with a wide variety of functions. They have not been identified for each CD but include receptors and ligands as well as adhesion proteins. Some of these CD have critical activities. CD4 and CD8 play a key role in antigen recognition whileCD135 is a cell surface receptor for growth factors. Hundreds of CD molecules have been identified today.
The anti-CD antibodies give all its usefulness to CD nomenclature. These antibodies are used especially in cell immunophenotyping. The cells of a given type can be recognized through different applications. For example cells can be dyed with immunostaining technique as immunofluorescence (IF) for example where an anti-CD antibody binds the associated CD protein. CD markers can also be targeted for diagnostic purposes. Indeed a high concentration of specific lymphocytes may indicate the development of a disease. B-cell and T-cell leukemia can be thus distinguished. CD may also be relevant to target particular cell with antibodies bearing drug molecules.
Proteogenix offers a wide variety of primary antibodies directed against CD markers to help you in your research!
