RE: [Histonet] endogenous peroxidase blues

From:"Patsy Ruegg"

Thank you all.  You all are such a great resource, it saves me so much time
to not have to reinvent the wheel everytime something troubling comes up.  I
am wondering if others have tried this Dual Endogenous Block from Dako for

-----Original Message-----
From: Veronique Andriessen [] 
Sent: Friday, January 28, 2005 3:51 AM
To: Histonet; Patsy Ruegg
Subject: RE: [Histonet] endogenous peroxidase blues

Hi Patsy,

I have encountered somewhat of the same problem with endogenous peroxidase
in acetone fixed frozen sections of acute pancreatitis, which is invaded
with white blood cells. I tested several ways of blocking, home made and
commercial including  glucose oxidase. I never got it to work properly
(believe me, I've tried!). What worked for me in the end was a new product
by DAKO called "Dual Endogenous Enzyme Blocking Reagent" (S2003) (Thank you
Mr. van der Loos!) It should work on cell preparations, frozen tissue and
FFPE tissue (according to the manual). I only have tested it on frozen
Just 10 minutes incubation at RT.

This is just my honest opinion, I hope this can help you.

Good luck

Veronique Andriessen BAS
Lab. Molecular Liver Cell Biology
Free University Brussels (VUB), Belgium

-----Original Message-----
[]On Behalf Of Patsy Ruegg
Sent: donderdag 27 januari 2005 23:10
Subject: [Histonet] endogenous peroxidase blues

Is there a sure fire way of iliminating endogenous peroxidase from
granulecytes in acetone fixed cytospins for hrp IHC?  Can I solve this
problem without changing to a non-hrp detection enzyme?  I am trying to
stain T lymphocytes in cytospins of sputum.  I do get cd3 positive
lymphocyte looking cells, but agressive efforts has not completely blocked
endogenous peroxidase in some of the larger cells with granules.
Thanks for your help,
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