RE: Principle of detecting apoptosis

Tom Mc Closkey (
Tue, 22 Oct 96 17:23:18 PDT

On Mon, 21 Oct 1996 08:25:21 +0300 (WET) Yashpal Agrawal wrote:

> Annexin V staining is becoming popular for detecting
>apoptotic cells.
>1. How does one exclude that the surface PS that one is detecting is not
>the normal component of cell membrane ?
>(I know non-nucleated cells (red blood cells) express PS, and also
>many nucleated cells (Cd34+) express PS).
>2. If an increase/decrease in Annexin V staining occurs, how can it be
>excluded that PS levels have not been up/down regulated, in contrast to
>assuming apoptosis as the cause. Membrane phospholipids flip-flop all the
>time in response to various modifiers.
I agree with you. My hesitation in using the annexin assay is the lack of a
good control molecule to determine:

1] amount of specific binding to non apoptotic cells [as you suggested]

2] amount of nonspecific binding to non apoptotic cells

In contrast, we have found TUNEL to be a very specific assay.

Name: Tom Mc Closkey
Date: 10/22/96
Time: 17:31:17

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Thomas W. Mc Closkey, Ph. D.
Director, Flow Cytometry
North Shore University Hospital
Cornell University Medical College
Manhasset, Long Island, New York
ph: 516-562-4641 fax: 516-562-2866

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