Tom Mc Closkey thomasm at
Thu Oct 29 15:05:41 EST 1998

--- On Wed, 28 Oct 1998 23:21:34 -0500 (EST)  plett at wrote:

>Question: Since the Annexin-V stain should be run with a live/dead stain
>(PI or 7AAD), wouldn't fixing make all cells permeable to these stains?
>Any comments?

	I'm not sure that annexin "should" be run with a live/dead stain.  
In a well characterized system in which the cells are dying by apoptosis, 
the assessment of membrane integrity yields information aobout cells which 
are early [membrane intact] and cells which are further along [membrane 
disrupted].  If the goal of the assay is to quantitate total apoptotic 
cells, annexin alone is sufficient [provided you verify that the annexin 
positiv e peak represents apoptotic cells and is not some nonspecific 
interaction].  The omission of PI for membrane integrity also allows the 
possibility to examine phenotypic, cell cycle, or other parameters of 


Thomas W. Mc Closkey, Ph. D.
Director, Flow Cytometry
North Shore University Hospital
Biomedical Research Center
350 Community Drive
Manhasset, Long Island, New York 11030
ph: 516-562-4844 [office]; 516-562-1135/4641 [lab]
10/29/98   12:15:50 PM
E-mail: thomasm at 

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