Antibody's specifity...

Mr. Hat 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:
> 
> ><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.
 
regards,
M.H.



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