[Histonet] Use of sodium borohydride in immunofluorescence

[Lucie Guernsey]

Hi,

I'm currently going over IHC SOPs that were written by lab members that
have long ago moved on to other jobs. One inconsistency that I've come
across is the use of sodium borohydride in immunofluorescence.

Our protocols state that a '0.5% sodium borohydride solution should be used
to block aldehyde fluorescence if staining CNS tissue in paraffin sections'
(this step is not included in our cryosection protocol).

Is there a particular reason that it should only be done in CNS tissue?
Seems to me that all tissues, regardless of type, should benefit from
blocking aldehyde fluorescence as the problem is caused by the fixative,
not the tissue type. Which leads me to the follow up question of: Our
cryosection protocol should also include sodium borohydride blocking if the
tissues were at any point fixed using an aldehyde fixative, correct?

There's a chance I have pregnancy brain and an obvious answer is slipping
past me, but my current opinion is that any and all immunofluorescence done
on paraformaldehyde (our usual fixative) fixed tissue should undergo sodium
borohydride blocking. Am I missing something?

Thanks for any help in clarifying this!

Lucie

Lucie Guernsey
UC San Diego
lguernsey at ucsd.edu