Hi,

I am currently using pHrodo Green AM as a marker for my target cells, which was used in a phagocytosis assay with my M1-like THP-1 cells and I have some questions regarding this specific dye:

(1) pHrodo Green AM was said to be a dye that is able to emit fluorescence on low pH conditions. However, when I observed the fluorescence using flow cytometry (FITC channel), I was able to see some strong fluorescence from the labeled target cells directly. Should this be happening? Considering that pHrodo dyes are supposed to only react with acidic conditions.

(2) I also perform co-culture between the target cells and the M1-like THP-1 (labeled with another dye). However, I saw that after co-culture, there seems to be a decrease in pHrodo Green fluorescence instead of an increase. Has anyone else observed this pattern?

Thank you.