“…As a result, the vesicles population studied can be quantified and/or classified according to the level of antigen expression ( Figure 2 B) [ 43 ]. Flow cytometry can also be used to enumerate EVs by adding, as an internal standard, a known number of fluorescent latex beads (Flow-Count Fluorospheres, Beckmann-Coulter, Brea, CA, USA) or using tubes containing already predefined bead numbers (TruCount tubes, BD Biosciences, San Jose, CA, USA) [ 37 ]. For smaller particles, such as exosomes (<100 nm in diameter) some other approaches can be introduced to allow their analysis by flow cytometry.…”