Cynthia:

I do endogenous peroxidase blocking as one of the first
steps in immunohistochem.  At least that's the way the
methods are suggested by my suppliers of antibodies. 
I'm guessing that the hydrogen peroxide could disrupt
the antigen-antibody bond.  If you are concerned, maybe
you should switch to an alkaline phosphatase method.

===
Catherine "Katie" Bresee Bennett
Laboratory for Experimental Pathology
Department of Veterinary Pathology
Michigan State University

*new* e-mail: bresee98@yahoo.com

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