[Histonet] IHC QC tissue

Rene J Buesa rjbuesa <@t> yahoo.com
Thu Feb 19 15:17:25 CST 2009

I usually did NOT use patients blocks and let me explain you why:
a patient with a positive and usually pathological entity has above normal epitope concentrations and when you use that highly positive target tissue to optimize the working concentration of your antibody it is possible that a much lower epitope concentration will either give a weakly positive or even negative reaction.
I always used the internal controls of normal tissues or normal tissues as positive controls and optimized my antibody working concentrations with them. By doing so I assured that anything above normal, would have a positive reaction more intense than my controls.
As to the blocks there is no big problem using them for long time, what you cannot use are previously cut sections that have been sitting around for more than 2 weeks, because the epitopes will oxidize and will give a negative reaction.
That is how I did it.
René J.

--- On Thu, 2/19/09, Clare Thornton <CThornton <@t> dahlchase.com> wrote:

From: Clare Thornton <CThornton <@t> dahlchase.com>
Subject: [Histonet] IHC QC tissue
To: "'histonet <@t> lists.utsouthwestern.edu'" <histonet <@t> lists.utsouthwestern.edu>
Date: Thursday, February 19, 2009, 1:08 PM

Does anyone have a policy on what they can use for IHC control tissue?  We use
patient tissue but there is some disagreement as to how old the case should be. 
We never exhaust a patient block, however, we do prefer to use more recent
tissues as to avoid any issues with antigenicity loss.  Of course, we always
check with a pathologist before cutting up patient tissue, but there are some
pathologists that are ok using more recent cases and some who are not.  What is
everyone else doing in the clinical setting?


Clare J.Thornton, HTL (ASCP)
Assistant Histology Supervisor
Dahl-Chase Diagnostic Services
417 State Street, Suite 540
Bangor, ME 04401
cthornton <@t> dahlchase.com

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