Dr. Kelly recently inquired:
"Dear friends,
we would like to ask some advice r.e. the interpretation of some
work we have been doing on induced sputum and BAL from normal
subjects and COPD patients. We have been using 'flow' to look at
the granulocytes, and examine the AV and PI staining in the
events which we have gated on, which we feel are in the region
in which one would expect to find granulocytes. Cells coming up
AV+PI- we interpret as apoptotic; AV+PI+ as necrotic. This would
seem to be conventionally how it is desribed in papers we have
looked at. However, we were not sure how one might interpret
cells which are AV-PI+? Are these just cells in an advanced
state of necrosis? Is there another interpretation?
We value any advice.
With best wishes. yours sincerely,
Martin Kelly"
We have noticed that isolated ("naked") nuclei, that shed the plasma
membrane (at least in some cell types) show this characteristics. To be on
the safe side, I suggest that in every case the objects with the unexpected
(and expected) characteristics measured by flow cytometry should be
additionally identified by light or electron microscopy (e.g after sorting).
This is especially important in studies of cell death because in many cell
types apoptotic and necrotic cells may not have the "classic" features of
apoptosis or necrosis, respectively.
Zbigniew Darzynkiewicz
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