Amy, one way that we have been able to assist people with those issues is to check on the pretreatment that is being used.  In the past, we have spoken to people using CK20 that said that they had received staining on breast tissue with their antibody.  They were pretreating it with enzyme digestion.  We suggested trying HIER with our Trilogy EDTA and it gave them the same specific staining in the GI tissue that they were receiving originally, but also eliminated the false positives that they were receiving in the breast tissue with the CK20.  Perhaps you should try an alternate epitope retrieval technique to see if that eliminates your sporadic false positive staining.  This may not apply to you, but it is just a suggestion to help you out in case the pretreatment is relevant to your tests.  If you have any further questions, let me know.

Jeff Gordon
Cell Marque Corp.
1-800-665-7284, Ext. 12
http://www.cellmarque.com

 -----Original Message-----
From: 	histonet-bounces@lists.utsouthwestern.edu [mailto:histonet-bounces@lists.utsouthwestern.edu]  On Behalf Of Amy Porter
Sent:	Thursday, September 09, 2004 4:59 PM
To:	Histonet
Subject:	[Histonet] Immuno question about CK markers

Need some help everyone.  I am taking the QIHC exam and am looking for a little advice about the grading system with regards to Cytokeratin 7 and Cytokeratin 20.  While I realize that they would like to have them mirror each other, will they down grade your score if both of your tumors are not completely negative for the opposite marker.  I have excellent staining in both tissues that are supposed to be positive for each marker and then foci's of sporadic staining (maybe 2 or 3 spots) that demonstrates positive reaction where the tumor is negative.  I am guessing that this is just the nature of the cytokeratin world, that not all tissue components will be negative.  Hope this makes sense and someone can give me some idea from their own experience.  Thanks in advance for all the help i know i will get.



Amy S.Porter, HT(ASCP) 
Michigan State University 
Department of Physiology 
Division of Human Pathology 
College of Human Medicine 
portera203@yahoo.com


		
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