cluster of differentiation antigen

initialism: CD
https://doi.org/10.1351/goldbook.13018
Any of a family of molecular markers on cell surfaces that may be used operationally to define phenotype, origin, and activation state of the cell.
Note: The CD antigens expressed by a T cell vary with its stage of development and thus with its role in the immune response.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1145 [Terms] [Paper]