Analysis of GC B-cell–derived vesicles by flow cytometry. Tonsillar GC B cells and T cells were stained with the cell membrane-specific probe, PKH26-GL, and then cultured for 2 hours. After this period, cell-free SN was collected and the presence of membranous vesicles was monitored by flow cytometry. (A) Dot plot representation of the forward scatter (FS) versus side scatter (SS) values of the SN containing GC B-cell–derived particles is shown. FL2 histogram obtained from the analysis of the same sample as in (A), either before (B) or after (C) filtering through a 0.1-μm pore membrane and of SN obtained from T-cell culture (D).