thresholding for apoptosis
ZBIGNIEW DARZYNKIEWICZ (darzynk@nymc.edu)
Mon, 05 Aug 1996 21:30:34 -0500
Using methods of apoptotic cell identification based on DNA content
analysis or the presence of DNA strand breaks there is a danger that
individual apoptotic bodies, fragments of broken cells, single
chromosomes or chromosome clumps from broken mitotic cells, all can
be mistakenly counted as individual apoptotic cells. Futhermore, when
cells are unfixed but treated with detergent or hypotonic solution, a
single apoptotic cell upon lysis can release numerous nuclear
fragments. I suggest that a threshold (on a DNA content coordinate)
should be used to exclude all objects with DNA content below 10 % of
DNA content of G1 cells. This may consistently underestimate the
percent of apoptotic cells, but it is a lesser error than erronously
classifying e.g. apoptotic bodies or nuclear fragments as individual
apoptotic cells.
Zbigniew Darzynkiewicz
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