misterhat at sbcglobal.net
Wed Jul 23 21:54:09 EST 2003
In article <3F1F1222.9000403 at NOSPAM.ucalgary.ca>, Bryan Heit
<bjheit at NOSPAM.ucalgary.ca> wrote:
> Comments within:
> Mike Clark wrote:
> Can you cite a single occurrence where antibodies show cross-specificity
> with a protein only 50% identical, unless it is recognizing a shared
> epitope? I did a quick check of pubmed and could not (not to say there
> isn't, I didn't look too closely).
PubMed is a poor tool for trying to reference materials such as this.
> >Also all antibodies have the potential to bind a large number of different
> >antigens and thus specificity can easily be seen to be a "relative"
> Specificity is not a relative concept, at least not in any of the lab's
> I've worked with. Antibody specificity is well demonstrated in the
> literature - it is very rare for an antibody raised against an antigen
> to identify other antigens, even when closely related. For example, in
> my lab we do a lot of work looking at the adhesion and signalling
> molecules involved in leukocyte recruitment. We use both murine and
> human models, and we need separate antibodies for both systems, even
> though it's not uncommon for the murine and human forms of these
> proteins to be greater then 95% at the amino acid level, and almost
> identical structurally.
Do you have any experience with developing hybridomas? With a little
muscle in the screening (and lots of time) you *can* manage to generate
antibodies with good cross-reactivity as long as you target (and there are
numerous ways to sculpt the response as desired) regions where
discontinuous epitopes are well preserved...three-dimensional homology, as
you know, is what is important for antibody recognition, not necessarily
just linear sequence homology. This is the key point that many fail to
keep in mind.
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