Re: CAP-negative controls


What it comes down to in my limited experience is what is required to convience
the CAP inspector that your IHC system is properly verified with controls.
Inspectors vary and some require more diligence than others.  If you get a
stickler, they could technically want you to use a neg control for each primary,
detection and pretreatment.  On the other hand, if you can demonstrate at the
microscope the validity of your system with what you usually do by pointing out
internal controls and concordance you will be alright.  I know this is not an
absolute answer but it is the best I can do.  Not likely, but even if you ran no
neg controls at all,  if your results are very good and can be demonstrated to
the inspector you may pass.  The adverse may also be true, that you may run all
the neg controls in the world and still may not be able to demonstrate to the
satisfaction of the inspector that your QA program is adequate.
This is a very important serious issue, perhaps there should be a Task Force or
something with members of CAP and our community to help resolve this issue.
My opinion.

Dionne Roberge wrote:

> Dear Histonetters,
> I have many people asking how the negative controls for Immunohistochemistry
> are being done by the professional community.   The CAP checklist,
> ANP.22570, requires a negative control for each antibody.  Are we using a
> negative control against every primary antibody used in the test or are we
> talking about the specie of the secondary in the detection system?  It also
> discusses the pretreatments are to match as well.
> So, how many labs can spare the necessary resources for multiple negative
> controls?  For example, we have one case where five antibodies are
> requested.  Since I am devils advocate, I have two that are polyclones and
> three that are monoclones.  One of the polys is enzyme treated, the other
> has no pretreatment.  The monos, one gets a high pH retrieval method, the
> other a citrate, the other gets none.  So are we doing five negative
> controls here?
> I bring this to the table because so many people want to know how to handle
> this.  I have had the opportunity to visit many labs and all have their own
> way and own interpretations of this.
> We need to have this clarified to provide consistency in testing and good
> standard of patient care and lab practice.  It would be nice to hear all
> points of view, laboratorians, pathologists, and those who have dealt with
> being inspected closely for this item, as well as those who have been
> inspectors and how they have handled this issue.
> I know this is a delicate item, but let's remain open minded.  We can make a
> positive difference here as a united professional group.
> Thank you in advance for the support and dedication.
> Dionne A. Roberge, HT(ASCP), QIHC
> Technical Service Representative
> DAKO Cytomation
> 800.400.3256 x5544

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