I believe that HT29 is an adherent cell line, in a paper (van Engeland et al Cytometry 24:131-139 1996) a PI+ annexin- population is described and is attributed to scraping during harvesting and therefore the cells suffer mechanical damage. It appears that this population is only seen if cells are labelled with annexin before harvesting. If cells are labelled after harvesting then they appear as annexin+ PI+ and may be considered secondary necrotic false positive results. Trypsinisation and EDTA also appear to permiabilise cells to annexin. Ian Titley PhD Leukaemia Research Fund Centre at the Institute of Cancer Research 237 Fulham Road LONDON SW3 6JB UK Tel: +44 171 352 8133 ext5134 Fax: +44 171 352 3299 E-mail: iant@icr.ac.uk On Tue, 26 Jan 1999 18:03:34 +0000 "Mireia Dalmau (S. Radioisotops Bellv.)" <SERV-RAD-BELL@bell.ub.es> wrote: > > > We have been analyzing apoptosis cell death in a human colon > adenocarcinoma cell line, HT29. We have obtained very nice and clear > results, but we usually detect a 3 to 5% annexin (-)/ PI (+) > population. > We can observe the same result with other cell lines and different > stimuli, and I have been asked to explain what is happening > there. > Many articles don't make any difference between PI (+) cells, beeing > annexin (+) or (-). Could someone suggest how to describe these cells ? > > Thank you very much. > > Mireia > ________________________________________________________ > > Mireia Dalmau > Servei de Radioisotops i Citometria de Flux > Campus de Bellvitge, Universitat de Barcelona. > C/ Feixa Llarga s/n. 08907 L'Hospitalet > > Telf. 93 402 42 06 FAX. 93 402 42 13 > e-mail: serv-rad-bell@bell.ub.es > __________________________________________________________
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