I would like to learn the meaning of the term "cluster designation", as in
CD4. My understanding is that the CD system is a system of nomenclature for
classifying lymphocytes according to their cell surface receptors. But what
does the term cluster refer to? I have asked several immunologists and gotten
different explanations. One said it relates to the cluster of antibodies
used to identify that particular cell (e.g., two or three antibodies would be
needed to identify a CD4 cell as CD4). Another said it is a system of
nomenclature that unites the lymphocytes serving the same function and having
a very similar structure in different species of animals (e.g., a CD4 cell in
humans, non-human mammals, and birds is a helper T cell). A third said the
cluster relates somehow to the number of amino acid chains in the receptor.
If someone would provide me with a accurate explanation, I'd really
appreciate it! Thank you!
