In article <1995May17.235349 at wehi>, <davis at wehi.edu.au> wrote:
>In article <dward.3.2FAFAE31 at magnus.acs.ohio-state.edu>,
>dward at magnus.acs.ohio-state.edu (Darrell E. Ward) writes:
>> I would like to learn the meaning of the term "cluster designation", as in
>> CD4.
>>This system is a method of identifying particular antigens on the surface of a
>cell. For most of these antigens, several monoclonal antibodies have been
>developed which recognise the same antigen. Since each antibody had a
>different name this rapidly became confusing. Now there is an annual workshop
>at which new monoclonal antibodies are examined and assigned either to an old
>or new CD, depending on the specificity obviously. The results of this
>workshop are published in various journals including Blood. There is a program
>called LDAD available from the NIH which is quite useful for this.
>>Hope this helps.
>>Ian Davis davis at licre.ludwig.edu.au>I would also like to add the following comments to the above explanation.
The application of the term CD has drifted over time from the original
definition. If you refer back to the first two Leukocyte Antigen Workshops
you will find that the term is Cluster of Differentiation.
The nomenclature originally applied to the antibodies and not the antigen.
Thus CD1 would have refered to the antibodies making up the cluster CD1
and the "CD1 antigen" is the antigen(s) recognised by the CD1 cluster of
antibodies. However it is now commonly accepted that the CD number refers
to the antigen and not the antibody. Where this makes a difference is
that now people talk about anti-CD3 antibodies as being antibodies to the
CD3 antigen. Under the original definition of CD this would be wrong and
might even be interpreted as anti-idiotypes to the CD3 cluster of antibodies.
Obviously they are two quite different things.
You therefor need to exercise caution when reading the literature and
to establish which definition of CD the writer was following.
It's just another of those immunological definition problems :-)
Mike Clark, mrc7 at cam.ac.ukhttp://www.path.cam.ac.uk/MikeClark/
--
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