<<Found out that if I ran the B5 fixed tissues through Lugol's and
thiosulfate
before immunostaining the CD30 staining was blocked or the antigenic sites
were modified,  causing false negatives.  Has anyone else observed this
effect?>>
Mark - Thank you for the very helpful CD30 info. Yes, I have found the same
thing with B5 fixed tissue for immuno. I discovered it while doing ER/PR
staining. The culprit seems to be the sodium thiosulfate. We use a
xylene/iodine solution to de-B5 before immunostaining. 95% alcohol in the
run-down removes the iodine crystals. We used to de-B5 after staining but
this is easier to remember.
Thanks again.
Marg
EMC