PI vs. 7-AAD Nuclear Staining

C.Reutelingsperger@BIOCH.RULIMBURG.NL C.Reutelingsperger at BIOCH.RULIMBURG.NL
Mon Mar 18 09:47:05 EST 1996

For those of you, who are using Annexin V-FITC and propidium iodide to measure apoptosis and have 
problems with dim PI positivity of viable and early apoptotic cells, you can wash your cells after 
staining with Annexin V-FITC and PI.

Using the binding buffer coming with the APOPTEST-FITC kit of NeXins Research, the washing step will
not result in a significant decrease of cellular bound Annexin V-FITC.

Doing this you will miss a possibly interesting subpopulation, namely those cells that are about to enter 
the secondary necrotic subpopulation. Those cells start to lose plasma membrane integrity without 
having a fully lost barrier (a free passage of PI to the intracellular DNA) and represent a late phase of 

So, it'll depend on your question whether or not to include a washing step following Annexin V-FITC and 
propidium iodide staining.

Chris Reutelingsperger

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