Annexin V binding to monocytes

From: DARZYNKIEWICZ ZBIGNIEW (DARZYNK@nymc.edu)
Date: Fri Jul 14 2000 - 16:26:29 EST


Dr. Kallas asks for interpretation of the finding that monocytes of the
septic patients are positive in terms of binding of Annexin V.

Monocytes ingest apoptotic bodies and remnants of the cells that undergo
apoptosis. During phagocytosis the plasma membrane of the monocyte fuses
with the plasma membrane of the apoptotic body and therefore
phosphatidylserine of the apoptotic body becomes exposed on the outer
leaflet of the phagocyte.
The phagocytes have also other attributes apoptotic cells - e.g. because
they ingest chromatin fragments of apoptotic cells they are positive in the
TUNEL assay, demonstrating numerous DNA strand breaks. The breaks, however,
are in the cytoplasm which can be detected by laser scanning cytometry or
image analysis but not by flow cytometry (see Bedner et al., Cytometry, 35:
181-195,1999).
Because not only "professional" macrophages are able to phagocytize
apoptotic bodies, but the neighboring epithelial cells or fibroblasts often
do the same, one has to be careful not to include these false positive
"apoptotic" cells while estimating apoptotic index.

Zbigniew Darzynkiewicz
Brander Cancer Research Institute
New York Medical College
19 Bradhurst Ave.
Hawthorne, NY 10532
tel: 914-347-2801
fax: 914-347-2804
http://www.geocities.com/z_darzynkiewicz



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