We have noticed blushiness on occasion with negatives retrieved with EDTA buffer, but biotin blocking steps usually minimize it enough to prevent interpretation problems.  Because we do our immunos on Ventana immunostainers we cannot increase the blocking step online, but maybe you have some options to "beef-up" the blocking step.

Sally Ann Drew-MT(ASCP)
Univ. of Wisconsin Hospital & Clinics
IHC/ISH Laboratory 
600 Highland Ave. VAH-DM223
Madison, WI 53792-2472
608-265-6596
sa.drew@hosp.wisc.edu


-----Original Message-----
From: Tara Miller [mailto:taratheht@hotmail.com]
Sent: Tuesday, July 22, 2003 2:04 PM
To: histonet@pathology.swmed.edu
Subject: nonspecific staining on neg. controls w/EDTA


Hi all,

I have been having difficulty trying to figure out why we occasionally have 
nonspecific staining on our negative controls when we use EDTA for HIER.  It 
is not on any specific type tissue - we've had staining on skin, thyroid, 
ect.  We haven't changed any of our methods, but this has just cropped up as 
a problem within the last month or so. Any suggestions?

Thanks in advance,
Tara Oakes HT
Central Dupage Hospital

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