Re: IH on Liver Tissue

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From:Abizar Lakdawalla <>
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Karen the liver may contain biotin which will produce background staining.
Simple way to evaluate this is by putting some DAB onto slides that have been
treated with H2O2 and washed. If you still get staining then the background is
due to endogenous peroxidases but if you get no staining then the background is
possibly due to biotin. Biotin activity can be blocked by using avidin followed
by free biotin.
abizar wrote:

> How can you successfully perform immunohistochemistry on slides of liver
> tissue using horse-radish peroxidase and DAB?  How do you quench the
> endogenous peroxidase in the tissue so everything doesn't turn brown?  I've
> tried 3, 10 and 15 % H2O2 in both methanol and di water for 20 min. up to 1
> hour with no success.  The tissues are formalin fixed and embeded in
> paraffin.  We then used a pH 6.0 citrate buffer/microwave antigen retrieval
> system for our primary Ab detection.  Even with all that the endogenous
> enzyme caused the false positive with the DAB.  Anyone have any
> suggestions?
> Thank you for all replies.
> Karen in Omaha

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