Subject:                              Time:  7:56 PM
  OFFICE MEMO         Control Slides                        Date:  10/5/99
Ann, 
This is what we do.
Cut your control slides and dry verticle at room temperature.
DO NOT DRY SLIDES IN AN OVEN.
Box horizontal in slide box.
Store at room temperature.
If the slides are not dried in an oven the antigen sites are being protected by
the paraffin.  They are protected as they are in a paraffin block except they
are thin sections. 
Example:  When cutting sections for Flow Cytometry thick sections are placed in
an eppendorf tube and later xylene is added to remove the paraffin.
PCR tissue is cut (RNA FREE ENVIROMENT) and placed on slides.  Later this
tissue is carefully removed from the slides and placed in sterile tubes and
deparaffinized. 
Due to lack of tissue our sections have been 5 microns.
We place the patient test tissue on the same slide as the control.  They are
then dried together.
I found that controls previously dried in an oven are not specific and totally
can become negative.
We have hundreds of different controls cut.  Haven't had any problem since we
stopped drying them.
If you place slides in a freezer you are adding extra moisture you don't want.
Everybody has different ways to do IHC.  This just works the best for us and
provides constant quality control for our IHC.  
Ann, I suggest you try several methods and decide which works best for you and
your laboratory.
Carol Ann Bobrowitz  
Medical College of Wisconsin