Re: [Histonet] CD3 clean with RB monos

From:Marvin Hanna

Hi Ray,

Thanks for the additional input. I stand corrected. Herceptin is a  
HUMANIZED mouse monoclonal antibody.  From Dr. Kimball's online  
Biology textbook, "The [Humanized] antibody combines only the amino  
acids responsible for making the antigen binding site (the  
hypervariable regions) of a mouse (or rat) antibody with the rest of  
a human antibody molecule thus replacing its own hypervariable  
regions." This helps reduce the problem of HAMA (human anti-mouse  
antibodies), which can cause damage to the kidneys and cause the  
therapeutic antibodies to be quickly eliminated from the human patient. 

I will also qualify my statement, "with up to a 10 times greater  
affinity" with "according to a number of IHC vendors of rabbit  
monoclonal antibodies". I have found at least 4 making claims of  
higher affinity. The Epitomics website claims that mouse monoclonals  
have affinities of "Nanomolar (~10-9 KD M)" and rabbit monoclonals  
have affinities of "Picomolar (10-12 KD M) possible", a thousand fold  
potential increase. I did not know that there are researchers who  
disagree with these statements  and appreciate you pointing it out. I  
agree additional research should be done.

According to a news release on the Epitomics website, they are  
providing humanized antibodies for therapeutic research. It is early  
to speculate that (possible) higher affinities of humanized rabbit  
monoclonals will provide a better therapeutic response in patients  
compared to humanized mouse monoclonals and will require many years  
of research and clinical trials to determine.

I also agree I have used rabbit monoclonal antibodies in IHC that  
have not given better results, and sometimes worse results, than  
their mouse monoclonal counterparts.

Best Regards,

Marvin Hanna

On Apr 23, 2007, at 4:32 PM, wrote:

> PS.
> As far as I know Herceptin (trastuzumab) is a HUMANIZED monoclonal  
> antibody and not a mouse or rabbit monoclonal.  While certainly  
> many things are possible, I'm skeptical of rabbit monoclonals, no  
> matter how great they are for IHC, going into human therapeutics in  
> light of the norm which is to humanize these reagents.  Unless you  
> were to "humanize" the rabbit monoclonal itself similar to  
> humanizing mouse monoclonals.
> Ray Koelling
> Phenopath Laboratories
> Seattle, WA
>  -------------- Original message ----------------------
> From:
>> Rena,
>> I agree that the epitomics website is great for learning about  
>> this technology
>> and I further agree it could be of help as has been mentioned  
>> before.  I am a
>> bit skeptical of claims of a 10-fold better affinity than mouse  
>> monoclonals as a
>> blanket statement.
>> At a previous meeting a while back we asked about claims of higher  
>> affinity and
>> couldn't  get a sufficient (to our mind) response.  To me that  
>> response would be
>> in the form of a side to side comparison, using the same  
>> immunogen, and with a
>> host mouse and rabbit side by side each producing monoclonals to  
>> same target to
>> see which might be better.  I believe the concept of a superior  
>> rabbit
>> monoclonal technology in terms of being able to break  
>> immunological tolerance in
>> the immunized systems, especially for some difficult targets, is  
>> probably right
>> on.
>> But simply breaking tolerance is not the same as producing higher  
>> affinity
>> antibodies.
>> For the blanket statement that rabbit monoclonals have higher  
>> affinity, I'd like
>> to see data comparing them to their (identical) target in a mouse  
>> host and see
>> data such as from Biacore, x-ray crystallography and that  
>> differences in somatic
>> hypermutation are indeed making these higher affinity.
>> That being said, I agree that the rabbit monoclonals have great  
>> use and even
>> more potential.  I've used several (many) that are far superior to  
>> their
>> counter-part mouse monoclonals.  However, I've used (and heard of)  
>> a few that
>> weren't as good.
>> So while I like rabbit monoclonals, use them, advocate for them  
>> and endorse the
>> suggestion you try them, I'm not convinced that  as a rule they  
>> have 10x higher
>> affinity than do mouse monoclonals.
>> Ray Koelling
>> Phenopath Laboratories
>> Seattle, WA
>>  -------------- Original message ----------------------
>> From: "Mildred Fail" 
>>> We have had quite a problem with CD3s on bone marrow biopsies  being
>>> "messy" both with mouse monoclonals and rabbit polyclonals. Protein
>>> block is used. Diluting the Ab out further lost some cells in the  
>>> lymph
>>> node control. We tried a  rabbit monoclonal. The staining is very
>>> specific and intense. The slide is beautifully free of extraneous
>>> staining. The higher dilution has not appeared to have effected the
>>> number of cells stained. Question       is why would the rabbit
>>> monoclonal produce a cleaner slide?
>>> Rena Fail
>>> Rena Fail
>>> _______________________________________________
>>> Histonet mailing list
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