Does using EDTA to detach adherent cell lines lead to false positives with annexin V flow analysis?

Question

Does using EDTA to detach adherent cell lines lead to false positives with annexin V flow analysis?

Answer 1

My quick answer is: if you make your EDTA solution to be 10% FCS, you should be alright.

Extended answer: First of all, you can't really get "false positives" in FACS. The truth is, in any culture of at least 1 million cells, you will get at least one cell that could stain positive for anything. This isn't a shortcoming of the machine, that cell will legitimately express the markers. Thats why you're interested in percentages with FACS. Even if one cells stains positive for something you know it shouldn't, if the percentage is close to 0, it doesn't matter.

Now what I think you mean by false positive is will the EDTA treatment artificially increase the amount of cell death in the culture independent of whatever you are trying to measure experimentally. The answer is probably a little, if you just use straight EDTA. Cells are always happier when they have proteins like FCS around and if you put them into a straight solution with no protein, some of them are going to start dying. However, you can easily reduce the amount of experimentally unrelated cell death if you just make sure to include FCS in your EDTA.

Anyway, I hope that helped. Good luck!