Re: CAP-negative controls
I think the CAP needs to clarify that question more. That has been a sticky
point since it first appeared on the checklist.
We run a negative control for each pretreatment we peform. If we have
four different pretreatments, then we have four negative controls.
During one inspection, the inspector insisted that we run a negative
control for each antibody. My pathologist, who was kind enough to allow me
to sit in at the multiheaded scope, put a tonsil stained with CD-45 on the
stage. He showed the inspector the areas where you expect to CD-45 positive.
Then he went to the epithelial area where CD-45 was negative. He asked the
inspector if he saw any epithelial cells picking up CD-45. My pathologist
told him that that was the negative control. The pathologist then placed a
skin stained for pan cytokeratin on the stage and did the same thing with
the cytokeratin. Showed the inspector the positive area, then showed him
some white cells and asked the inspector if any of the white cells were
picking up CK. That seemed to answer the inspector questions and he moved
on. Now, keep in mind that this was a few years ago and I don't know how
savvy the inspector was with IHC. I'll let you know what happens this year
when we have an on-sight CAP inspection.
Joe Nocito, BS, HT (ASCP) QIHC
Pathology Reference Lab
San Antonio, Texas
----- Original Message -----
From: "Dionne Roberge"
Sent: Thursday, July 11, 2002 9:36 PM
Subject: CAP-negative controls
> Dear Histonetters,
> I have many people asking how the negative controls for
> 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
> 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
> this. I have had the opportunity to visit many labs and all have their
> 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
> 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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