Cluster of Differentiation is a naming protocol used for identification of cell surface molecules. It provides a framework for classification and research of monoclonal antibodies.
Physiologically, most CD molecules act as receptors (or ligands), and initiate a signalling cascade, though some are responsible for cell adhesion and other processes.
Leukocyte CD expression:
| Cell type | CD markers |
|---|---|
| Stem cells | CD34+, CD31-, CD117 |
| All leukocyte groups | CD45+ |
| B lymphocyte | CD45+, CD19+, CD20+, CD24+, CD38, CD22 |
| T lymphocyte | CD45+, CD3+ |
| T regulatory cell | CD4, CD25 |
| Cytotoxic T lymphocyte | CD8+, CD45+, CD3+, |