[Histonet] CD3 clean with RB monos

Marvin Hanna mhanna <@t> histosearch.com
Mon Apr 23 06:05:50 CDT 2007

Hi Rena,

I think it mainly has to do with a rabbit antibody's greater affinity  
for human tissue versus mouse antibodies. We seem to be closer to  
rabbits on an evolutionary scale than mice. Up until recently, all  
rabbit antibodies have been made by injecting rabbits with the  
antigen, which produces polyclonal antibodies, a mixture of  
antibodies targeting that antigen. A few years ago, researchers  
developed the technology to manufacture rabbit monoclonal antibodies  
using hybridomas, the method used to manufacture mouse monoclonals,  
which produces antibodies with greater specificity, a single clone.   
So, a rabbit monoclonal can have the same specificity as a mouse  
monoclonal, with up to a 10 times greater affinity for it's human  

I've visited a few hundred IHC labs over the last few years and  
utilized rabbit monoclonals in many of them. Consistently, histotechs  
and pathologists commented on the cleaner backgrounds and stronger  
intensity with them. I assume the greater affinity for human targets  
means a less affinity for anything that is not the intended target,  
creating less background. The promise of a new round of antibodies  
with a 10 times greater affinity for their targets could be a big  
benefit for IHC labs and cancer patients.

There is also research work going on to use rabbit monoclonals  
therapeutically. With the successes so far in IHC, it makes you  
wonder if drugs like Genetech's Herceptin, which is a mouse  
monoclonal that blocks the her2 gene and has been shown to double the  
chance of survival of patients who take it, could be even more  
successful as a rabbit monoclonal.

Best Regards,

Marvin Hanna

On Apr 22, 2007, at 9:37 PM, Mildred Fail wrote:

> 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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