-------- On Mon 3/27/00 10:49 [oberyszyn.2@osu.edu] wrote -------- I have a user who is looking at Annexin V- FITC/PI staining of Caco-2 cells. The problem that I am encountering is that the untreated, Annexin V- FITC only stained cells are a log higher than untreated/unstained cells (see attached PowerPoint slide). A possible explanation can be found in Blood 1999;94(5):1657-1664. PubMedID: 10477690. Quote: "Mild acid treatment of polarized Caco-2 cells ... markedly increased the anionic phospholipid content on the basolateral surface membrane". You can download the abstract by coping the article's PubMed ID and pasting it into the search field at http://www.ncbi.nlm.nih.gov/PubMedOld/medline.html CaCo-2 is a colon carcinoma and I assume that cells were removed from plastic by trypsin-EDTA, which, in my opinion, is close enough to "mild acid treatment". You may want to contact the author directly: C.B. Hansen [CBHa@novo.dk]. He probably knows everything about "dramatic relationships" between Annexin and CaCo-2 :o) Best Regards, Yuri ------------------------------------------ Yuri Kudinov, postdoctoral fellow SVMC, Immunotherapy Lab 201 S.Alvarado St., Ste 312 Los Angeles, CA 90057-2354 ------------------------------------------ PS. Here is another article showing that trypsin can mess up with Annexin V staining. See Cytometry 1996 Jun 1;24(2):131-139. PMID:8725662 I was surprised to find that certain tumor cell lines have elevated levels of phosphatidylserine (PS) in the outer-leaflet constitutively. See PMID:2032247, 8075308, 9369853, 1448786, 2717615 Other cell line can expose PS during activation and differentiation [PMID: 950621, 9731106]. For example, B lymphocytes (normal and transformed ) can expose PS after treatment with Ca(++) ionophores. >From the other hand, many cells commit suicide without exposing PS [PMID: 10600532, 9506954]. Isn't it exciting?
This archive was generated by hypermail 2b29 : Wed Apr 03 2002 - 11:55:41 EST