AW: [Histonet] Mucin blocking reagent for IHC

Gudrun Lang gu.lang <@t>
Mon Dec 15 08:22:34 CST 2008

With the polymer-systems of IHC detection it is often seen, that in some
tissueparts an unwanted background occurs. It is said, that the large
polymers are trapped in OH-reach tissues like mucin and collagen. And also
an additional washing step doesn't erase that. The polymers are labelled
with Peroxidase. The trapped peroxidase leads to the colourdevelopement.

Gudrun Lang
Linz, Austria

-----Ursprüngliche Nachricht-----
Von: histonet-bounces <@t>
[mailto:histonet-bounces <@t>] Im Auftrag von John
Gesendet: Montag, 15. Dezember 2008 07:15
An: Aprill Watanabe
Cc: histonet <@t>
Betreff: Re: [Histonet] Mucin blocking reagent for IHC

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

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

> 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>
> _______________________________________________
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> Histonet <@t>

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