There is a peroxidase quench that will block ALL forms of peroxidase,
totally.  This is the glucose oxidase method.   

Hsu H-M, et al Am J Pathology 188:209-217,1984

Andrew SM and Jasani G Histchem J 19:426-430, 1987

Vector provided me with the exact protocol


>Date: Mon, 10 Jul 2000 14:43:03 -0400
>From: Jeff Crews <jcrews@organo.com>
>Subject: Re: IH on Liver Tissue
>To: kkdulany@unmc.edu, histonet@pathology.swmed.edu
>
>     With extremely bloody tissue like spleen or liver, it is sometimes 
>     impossible to quench all of the peroxidase present in the blood. Try 
>     an alkaline-phoshatase detection system.
>     
>     Jeffrey Crews, HTL (ASCP)
>     Organogenesis, Inc.
>
>
>______________________________ Reply Separator
_________________________________
>Subject: IH on Liver Tissue 
>Author:  <kkdulany@unmc.edu> at internet
>Date:    07/10/2000 11:03 AM
>
>
>How can you successfully perform immunohistochemistry on slides of liver 
>tissue using horse-radish peroxidase and DAB?  How do you quench the 
>endogenous peroxidase in the tissue so everything doesn't turn brown?  I've 
>tried 3, 10 and 15 % H2O2 in both methanol and di water for 20 min. up to 1 
>hour with no success.  The tissues are formalin fixed and embeded in 
>paraffin.  We then used a pH 6.0 citrate buffer/microwave antigen retrieval 
>system for our primary Ab detection.  Even with all that the endogenous 
>enzyme caused the false positive with the DAB.  Anyone have any 
>suggestions?
>Thank you for all replies.
>Karen in Omaha
>     
>     
>     
>
>
>
>
Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303