When it was my job to perform quality assurance testing of ER/PgR IHC 
kits, I used a 'validated' slide (actually, a photomicrograph) with well 
documented ER or PgR positive cells, stained with a master kit.  Various 
positive cells were labeled as +4, +3, +2, +1, and +0 (negative) -yes, 
very subjective, but two people had to agree on the positive cells.   In 
the process of evaluating the quality of a new kit, or testing the 
stability of an on-market kit - I used the kit to stain known positive 
tumors.  I counted each +4 through =0 cell within a pre-determined grid 
area to ensure the kit on test was giving appropriate results by 
conforming to the quality assurance guidelines pre-established for that 
test.   (similar to what Greg has stated below)
I'm sure that with the advent of image analysis, my job would have been 
much simpler and much less subjective.  Thank Goodness they killed that 
product line, and I was able to go on to more interesting work.
I'm curious as to how current antibody manufacturers perform stabilty 
testing on their products.

Jackie O' 




"Barry R Rittman" 
Sent by: histonet-bounces@lists.utsouthwestern.edu
09/09/2004 01:43 PM

 
        To:     "histonet" 
        cc: 
        Subject:        RE: [Histonet] quantitative graded scale for IHC


I would agree with the comments below from Greg.

The major problem with comparing stain intensities between sections is
that you generally have no real measure of the section thickness for an
individual section. If you are cutting at 5 microns there can easily be
a one micron difference between sections, which translated into
differences in volume of tissue and intensity of staining can be
significant. One way around this is to prepare a block of tissue that is
embedded with the sample. The block can be of a homogeneous protein
material stained for example with a Procion dye. 
You can, if you have no social life, prepare sections of this material,
dissect out a measured area with a blade (using a dissecting scope) and
weigh it. You can then relate this volume of tissue to its intensity of
staining and work back to relate this to section thickness. 
If a cylinder of this material is embedded with the block it provides a
built in control that will allow comparison between sections.
his does not of course take into account any differences in staining due
to differences in staining conditions for different slides.
Barry

-----Original Message-----
From: histonet-bounces@lists.utsouthwestern.edu
[mailto:histonet-bounces@lists.utsouthwestern.edu] On Behalf Of Greg
Dobbin
Sent: Thursday, September 09, 2004 7:54 AM
To: Carla M Conway
Cc: Histonet@lists.utsouthwestern.edu
Subject: Re: [Histonet] quantitative graded scale for IHC 

Hi Carla,
I certainly may be corrected by others on this but I personally don't 
think you will obtain statistically valid data by grading intensity of
the 
reaction between cells or fields or sections. There is just so much 
room for subjectivity and for that matter, variability between runs or 
perhaps even between slides within runs!

What you may want to try is calculating a ratio of positive to 
negative (perhaps pos. cells vs. neg. cells in a given area). For 
instance: place a grid with 50 or 100 intersects on the computer 
monitor, choose a microscopic field (in a random or systematic- 
random manner), and then at each intersect decide whether the 
reaction at that point is positive or negative. If at any particular 
intersect you have trouble to decide whether it is  pos or neg, have 
a system that does not permit subjectivity, such as: for such points 
where the call could go either way, look at the space imediately to 
the left of the y-axis and above the x-axis and then make your 
decision. Determination of the number of fields you need to sample 
in order to obtain statistically valid data is very important and a 
matter for a statistician to explain and/or determine for you (which I 
most definately am not) unless you happen to have that training 
yourself.

Another idea would be to have the image analysis software either 
measure the area of or count the number of pixels in a given area 
(field) that are "this red or redder". This involves choosing a 
relatively arbitrational threshold for the degree of redness that is to 
be measured or counted and applying the exact same setting to all 
other fields and sections in the study. My personal experience 
(using Bioquant NOVA) has been this sounds great in theory but 
was very difficult to pull off! The good old-fashioned counting was 
much more reliable and for that matter, easier to defend in 
presentation or publication. 

I am eager to hear other ideas or methods that might also work! 
Good luck.
Greg

To:                              Histonet@lists.utsouthwestern.edu
From:                            "Carla M Conway" 
Date sent:                       Thu, 9 Sep 2004 07:22:02 -0700
Copies to:                       Subject: [Histonet] quantitative
graded scale for IHC 

> Hello,
> 
> I would like to devise a quantitative graded scale for IHC results
which
> would provide more info than just +/- staining.
> I have a reference where  IHC staining intensity was rated (from pale
pink
> to dark red) using alkaline phosphatase/Vector-Red, however we are
using
> Envision+/AEC which seems to be an all or nothing (red or no red)
chromogen
> with no gradation. We just received ImagePro image analysis software,
so
> this may be another route to try.  Thanks in advance for any comments
or
> suggestions you may have.
> 
> Sincerely,
> 
> Carla Conway
> Western Fisheries Research Center
> Seattle, WA
> 
> 
> 
> _______________________________________________
> Histonet mailing list
> Histonet@lists.utsouthwestern.edu
> http://lists.utsouthwestern.edu/mailman/listinfo/histonet




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Greg Dobbin
Pathology Lab
Atlantic Veterinary College, U.P.E.I.
550 University Ave.
Charlottetown, P.E.I.
Canada,  C1A 4P3
Phone: (902)566-0744
Fax: (902)566-0851
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Happiness is a journey, not a destination.

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