responses to pe-viability detection

KUKURUGA@medmail.med.umich.edu
Mon, 27 Jan 1997 09:07:41 -0500 (EST)

General response . . . 1) PI works well as a viability marker, as most know.
With a low concentration of PI, it's easily separated from PE. 2) 7AAD also
works well, as one other message indicated, particularily since the resultant
fluorescence is >650. Both are excluded from live cells, and serve well to
detect damaged or dead cells.
Comments on FDA . . . 1) while FDA is a good indicator of esterase activity,
it's not necessarily the best "viability" indicator. The fluorescein
product resulting from the metabolism of FDA can readily leak out of cells, so
the carboxy form is recommended. 2) I've seen a similar compound --
Molecular Probes' calceim AM viability probe -- actively "pumped" from cells
expressing p-Glycoprotein 170, so "green-negative cells" are not necesarily
"dead." Usually, when dyes such as FDA are employed as a viability marker, PI
has been used (quite necessarily) in combination to confirm the results.

MAK.

Mark A. KuKuruga
University of Michigan Flow Cytometry
kukuruga@medmail.med.umich.edu