Principle of detecting apoptosis with Annexin V

Yashpal Agrawal (yagrawal@messi.uku.fi)
Mon, 21 Oct 1996 08:25:21 +0300 (WET)

Hi every body,
Annexin V staining is becoming popular for detecting
apoptotic cells. I understand this is because Annexin V stains membrane
phosphatidylserine (PS), which is a marker of apoptotic cells. Is it this
simple ?. Am I understanding the principle correctly ?

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.

Please could some one enlighten me. I am sure I have misunderstood the
Annexin V assay.

Thanks,
Yash Pal Agrawal
Kuopio, Finland
yagrawal@messi.uku.fi