[Histonet] Mucin blocking reagent for IHC

[John Kiernan]

Please explain "mucin trapping the DAB". Are you sure that this is not genuine immunohistochemical  localization of the antigen?

At neutral pH DAB cations are attracted to tissue polyanions (in mucus, cartilage etc). The attracted DAB should not be oxidized to a brown insoluble polymer in the absence of peroxidase.

The only working peroxidase molecules in an immunohistochemical preparation should be those specifically bound at the site recognized by the primary antibody. Brown staining of mucus suggests the presence of peroxidase in the DAB-H2O2 final incbation solution. This would catalyze the oxidation of tissue-bound DAB. More washing after the last HRP-containing reagent might help.

John Kiernan
Anatomy, UWO
London,  Canada
- - -
----- Original Message -----
From: Aprill Watanabe <awatanabe <@t> tgen.org>
Date: Friday, December 12, 2008 17:26
Subject: [Histonet] Mucin blocking reagent for IHC
To: histonet <@t> lists.utsouthwestern.edu

> I am staining CA19-9 on pancreas and have a good amount of mucin 
> trappingthe DAB.  Is there a product that either blocks 
> mucin or something else that
> will limit the mucin effect?
> 
> Aprill Watanabe, B.S.
> Research Associate
> Integrated Cancer Genomics Division
> Tissue Microarray Center (TMA)
> Translational Genomics Research Institute (TGen)
> main: 602-343-8822
> Fax: 602-343-8840
> awatanabe <@t> tgen.org
> www.tgen.org
> 
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