Sally: The simple answer to the question of whether or not biotin blocking is required is ‘no’. As you stated in your inquiry, blocking need only be performed when excessive nonspecific staining, attributable to endogenous biotin, is observed.
For what its worth, I think that some folks believe biotin blocking is required because they've miscontrued information contained within the College of American Pathologists AP checklist, which states: “If the laboratory uses an avidin-biotin complex (ABC) detection system...is there a policy that addresses nonspecific false positive staining from endogenous biotin?" As written, this question only implies that an assessment of false positive staining be performed. Therefore, provided that the lab conducts the recommended assessment, documents their results within appropriate policies/procedures, and then incorporates biotin blocking steps where they're needed, it does not have to perform blocking at all times. I'd welcome additonal input if my understanding is incorrect. Regards, Joe Myers, M.S., CT(ASCP) ------------------------------ Message: 9 Date: Tue, 1 Sep 2009 08:31:56 -0400 From: Sally Price <sprice2...@gmail.com> Subject: [Histonet] Endogenous biotin blocking To: histonet@lists.utsouthwestern.edu I recently had a discussion with one of my coworkers about the need/requirement for blocking of endoegnous biotin whenever an avidin-biotin detection system is used, and I was hoping that the IHC experts on the histonet might be able to provide us with some feeback. Its been my understanding that blocking is only necessary when one is certain that background staining is caused by endogenous biotin, but maybe I'm off-base here. I look forward to eveyone's input. Sally _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet