CAP-negative controls

From:Dionne Roberge

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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