Antibody's specifity...

Mr. Hat misterhat at
Wed Jul 23 21:54:09 EST 2003

In article <3F1F1222.9000403 at>, Bryan Heit
<bjheit at> wrote:

> Comments within:
> Mike Clark wrote:
> ><snip>
> >

> 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"
> >concept.  
> >
> 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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