[Histonet] Mucin blocking reagent for IHC

[Mark Tarango]

Just last week I saw DAB staining mucin for p53 (which should be nuclear
staining).  We were using Ventana's Iview kit which uses avidin and biotin
as links.  After we added the a/b block, this unwanted staining completely
disappeared.  I'd suggest adding a blocking step.

Mark

On Sun, Dec 14, 2008 at 10:15 PM, John Kiernan <jkiernan <@t> uwo.ca> wrote:

> 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
> >
> > _______________________________________________
> > Histonet mailing list
> > Histonet <@t> lists.utsouthwestern.edu
> > http://lists.utsouthwestern.edu/mailman/listinfo/histonet
>
> _______________________________________________
> Histonet mailing list
> Histonet <@t> lists.utsouthwestern.edu
> http://lists.utsouthwestern.edu/mailman/listinfo/histonet
>