[Histonet] negative IHC controls

[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
Histopathology
Hinchingbrooke Hospital
Huntingdon
England
  -----Original Message-----
  From: histonet-admin <@t> lists.utsouthwestern.edu
[mailto:histonet-admin <@t> lists.utsouthwestern.edu]On Behalf Of vermast
  Sent: 08 October 2003 21:57
  To: histonet <@t> lists.utsouthwestern.edu
  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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