Regaurding IHC controls, I agree that having a control on each slide is
great. So is having an isotype negative for each one. As is having a non
positive tissue labeled the same as the positive.
The control on the same slide can often be missed by the drop zones of
many automated stainers, so it might be good to have a couple on each slide
on top and on the bottom, probably positive and negative too, just to be
sure. One could, perhaps use a microarray on each slide.
We can really spin our wheels on the subject of control tissues. There
are good reasons for all these controls, but we have to be reasonable about
how much effort goes into them as opposed to how much information you can
get out of it. Running 5 control slides for each actual test slide, and not
being able to tell the test from the control on the same slide is counter
productive. Then again so is running just one slide and not knowing if it
worked or not.
We need to be responsible enough to anticipate where the problems are
most likely to occur and run controls for these situations, working with
doctors that actually care to look at the controls. Some actually don't even
care about positive controls much the less negative! Ultimately it is their
call to make and they need to be confident in your dilligence, but also know
you aren't wasting time and money on controlling too many things that they
may deem irrelevant. It is a balancing act.
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