[Histonet] opinion on heating slides prior to IHC

[Jeffrey Thompson]

Dear Histonetters,
 
We have an ongoing debate in our lab regarding preparing tissues for staining. I would like to get input from the wider community to use in our discussions.
 
In all cases the tissues in question were from paraformaldehyde perfused rat brains that were sectioned at 10 or 20 microns on a cryostat and affixed to Superfrost Plus slides and stored in slide boxes within ziplock bags with dessicant at -80 C. 
 
So the debate is what happens when preparing to stain:
 
One camp thinks that the slide box/bag should be warmed to 50 C before removing the slides to drive off any water from condensation on the tissues. Following this they will remove the slides to be stained and return the box to the freezer. After applying the PAP pen border then proceed with the staining protocol with serial alcohol rehydration as the first step.
 
The other camp feels that heating the slides may potentially 'cook' the epitopes as well as being redundant since the first incubation in 100% EtOH will drive off any water which will be immediately added back in by the procedure anyway. They favor removing the frozen slides from the box and immediately returning the box with remaining slides to the freezer, and air drying the slides to be stained at RT before applying the PAP pen border
 
The epitopes of interest are various intracellular and transmembrane cell type markers and enzymes common in rat neural tissue.
 
Any input will be appreciated
 
Thanks,
 
J Thompson