[Histonet] Re: endogenous peroxidase

[David A. Wright]

Hi Kim and Histonet
Just a suggestion - I include sodium azide (to 0.01% final) in my antigen retrieval buffer. 

As we are repeatedly warned, azide is deadly to peroxidase activity, but this also includes endogenous peroxidases, so we can turn it to our advantage too. By the time I do my 'real' peroxidase staining,  any residual free azide has long been washed away but continues to poison the endogenous enzyme. 

This has worked for me for neutrophils infiltrating brain injuries. Without using any other peroxidase quenching I get no background staining (including the neutrophils), but I can DAB-detect them just fine after azide if I use an anti-myeloperoxidase primary.

-hope it works for you
-David
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Original Message:
Histonet Digest, Vol 103, Issue 14 Message: 13
Date: Mon, 11 Jun 2012 09:37:13 -0700 (PDT)
From: Kim Merriam <kmerriam2003 <@t> yahoo.com>
Subject: [Histonet] endogenous peroxidase in eosinophils

Anyone have tips for quenching endogenous peroxidase in eosinophils? Our standard px block is not doing the job (Biocare Peroxidazed-1).

Thanks,
Kim

Kim Merriam, MA, HT(ASCP)QIHC
Cambridge, MA
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David A. Wright, Ph.D.
University of Chicago
Section of Neurosurgery, MC3026