RE: [Histonet] negative IHC controls

From:"Nick Kirk"

In my opinion you should always run a negative control with every patient run. For starters, how do you know
a. Your blocking solutions have worked?
b. You haven't got endogenous biotin activity (especially in liver biopsies) giving a false positive?
c. You haven't got a contaminant?
For clinical assurance and governance reasons alone I would have thought that negative controls are essential.
I think the reasons for DAKO selling the two reagents separate is for commercial reasons only (they can charge more) rather than any fact that people aren't using them.
In the UK it is considered "best practice" to use negative controls and not to do so would be frowned upon by the National External Quality Assurance Scheme (NEQAS) who monitor the quality of immuno carried out by hospitals in the UK, which nearly every lab in the UK and many more overseas are signed up to.
No negative controls is poor quality control in my book.
Nick Kirk
Hinchingbrooke Hospital
-----Original Message-----
From: []On Behalf Of vermast
Sent: 08 October 2003 21:57
Subject: [Histonet] negative IHC controls

I would like to get a feel for how many out there are running negative control slides for IHC. 
In our lab we do just a handful of antibodies and initially I had been running a negative control slide with each patient slide.   After much discussion with our pathologists, we decided to omit these negatives (which were conistently negative) and continue to just run a positive control with each primary antibody for the run.  We use the Dako autostainer and prediluted primaries.  The decision to stop running negatives also coincided with Dako's decision to sell the negative control sera separately from the primaries (they used to come packaged together).  Perhaps I assumed that discontinuing to pair these reagents together meant that few labs were using the negatives.
Anyhow, after having reviewed the last QMPLS (Canada) survey committee comments, I believe the committe would like a negative control run with each patient tissue slide in order to evaluate background  (they have used NCCLS guide pages as reference).  Incidentally we weren't a part of the survey due to a technicality.
Any help or advice would be appreciated.
L. Vermast
Stratford, Ont.

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