[Histonet] IHC pos. & neg. control question

Thu May 19 17:12:40 CDT 2011

Pete,

Can't argue with that.  I think for the sake of expediency most clinical
services run a "known" positive and a patient slide for negative.  In
the case of H. Pylori, for instance, we may cut a box of control slides
and it's possible to go through the area where the organisms were.  This
also happens with controls that demonstrate positivity by other means
epithelium, tumor, etc.  We may have to re-run tests in these
situations. I believe we are similar to many clinical labs in our
reliance on known positives.
tj

-----Original Message-----
From: Pete.Pedersen <@t> HealthONEcares.com
[mailto:Pete.Pedersen <@t> HealthONEcares.com] 
Sent: Thursday, May 19, 2011 2:54 PM
To: Thomas Jasper; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC pos. & neg. control question

Thomas,

Agreed, however, how can you say with certainty that the control is
still good, or the antibody is still performing optimally?
Hypothetically speaking, if you had a known positive control and ran it
like a patient specimen (positive and negative) and had staining in the
negatively stained control that you had been only running as a
positively stained control prior, how would you proceed? What good is a
positive control without if it is not treated identically as patient
tissue. If you had none specific staining in a patient negative but is
was also there in your known positive control which you stained
negatively as well, then you could mark up to nonspecific staining to
reagent or IHC user error. If the negatively stained positive control
stains truly negative and the patient negative has nonspecific staining
then you would know patient tissue is compromised or has been mistreated
somewhere along the way because your positively stained and negatively
stained positive controls demonstrate the staining was done correctly,
correct? 

Pete Pedersen   B.S. HTL (ASCP)
Anatomic Pathology Supervisor

-----Original Message-----
From: Thomas Jasper [mailto:tjasper <@t> copc.net] 
Sent: Thursday, May 19, 2011 1:39 PM
To: Pedersen Pete; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC pos. & neg. control question

Pete,

When you run a positive control.  The tissue is already a known positive
(or it should be) for whichever antibody you are running regardless of
prior handling.  It would be impossible for this not to be so.  However,
with a negative, the concern is seeing how the patient tissue turns out
when subjected to all the same conditions, minus the antibody.  
tj

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of
Pete.Pedersen <@t> HealthONEcares.com
Sent: Thursday, May 19, 2011 12:31 PM
To: GDawson <@t> dynacaremilwaukee.com; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC pos. & neg. control question

Glen,

If I am to understand you correctly you are saying control tissue is not
treated the same as patient tissue, therefore is useless as a negative
control correct? Then inversely doesn't that mean the same thing towards
the use of a positive control? How can you guarantee the positive
control tissue was treated the same as the positive stained patient
tissue? According to your logic it cannot. Therefore, without the use of
a negative control how can you say the staining seen in the positive
control is truly positive and not artifact? Best practice says use
positive and negative patient and control tissue. Please enlighten me if
you know anything to the contrary? 

Pete Pedersen   B.S. HTL (ASCP)
Anatomic Pathology Supervisor

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Dawson,
Glen
Sent: Thursday, May 19, 2011 12:32 PM
To: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] IHC pos. & neg. control question

IMHO: Running any piece of tissue as a control that does not belong to
the patient being tested makes zero sense.  Because it would not be from
the patient tissue being tested, how do you know if it was handled the
same as the patient tissue?  For example:

1) Were they processed the same way?
2) Did the patient tissue dry out in the OR before it was delievered?
3) Was the patient tissue ever irradiated?
4) Does the patient tissue contain any of a number of substances that
could cause non-specific staining.
5) Was the patient abducted by aliens?

My point is that running a piece of tissue as a negative control that is
not even from the patient being tested throws all of the conditions that
the patient tissue was exposed to prior to and during processing out the
window.  This makes NO sense.

Glen Dawson  BS, HT(ASCP) & QIHC
IHC Manager
Milwaukee, WI

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Curt
Tague
Sent: Thursday, May 19, 2011 11:04 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] IHC pos. & neg. control question

I got this email from a pathologist today. we have always run a positive
with the patient tissue and a negative, the same patient tissue, and had
no
problems. Am I missing something. Is there any documented regulation
dictating what needs to be used for the controls. In some cases if we
get
one slide of patient tissue, then we will use the pos. and neg. cont.
from
the same block but typically it's the pt. tissue that is used for the
neg.
control. Thanks for your guidance.

Email:

"I received slides on sentinel lymph node biopsies with a positive
control
on the same slide as the breast tissue, but the negative control was
just
the patient's lymph node and did not have the corresponding section used
for
the positive control.  The patient's own tissue cannot be used as a
negative
control.  The tissue that stained positively must serve as the negative
control without the antibody.  This is critical and you need to correct
that
immediately."

Curt

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