Page 60 - Veterinary Immunology, 10th Edition

When advances in immunology made it possible to produce highly
VetBooks.ir specific antibodies against individual cell surface proteins (Chapter

9), it was shown that mammalian cells expressed hundreds of
different proteins on their surface. Initially, each protein was given
a specific name and often an acronym as well. It was soon

apparent, however, that such a system was unworkable. In an
attempt to classify these proteins, a system has been established
that assigns each protein to a numbered cluster of differentiation

(CD). In many cases, a defined CD denotes a protein (or related
proteins) of specific function. For example, the protein CD14 binds
bacterial lipopolysaccharides and controls TLR4 responses. As of
March 2016, numbers up to CD371 have been assigned.
Unfortunately, CD numbers provide no clue to a molecule's

function. In practice, therefore, immunologists tend to use a mixed
system employing both a CD number and an abbreviation that
denotes the function of a molecule. For example, CD32 is also

called FcγR1. A list of selected CD molecules can be found in
Appendix 1.

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