[Histonet] CD3 clean with RB monos

Tue Apr 24 01:32:08 CDT 2007

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.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/ 
Monoclonals.html

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.

http://www.epitomics.com/technology/tech.html

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
mhanna <@t> histosearch.com

On Apr 23, 2007, at 4:32 PM, koellingr <@t> comcast.net 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: koellingr <@t> comcast.net
>> 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" <failm <@t> musc.edu>
>>> 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
>>>
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