Characterization of the interaction of BM FL B cells with stromal cells. (A) Purified FL B cells (n = 4) were cocultured with BM-MSCs pretreated with TNF/LT or FL-derived EVs for 3 days. On day 3, CD19/CD20⁺ viable B cells were analyzed by flow cytometry for CD86 membrane expression (left; expressed as a ratio of mean fluorescence intensity compared with B cells cocultured on untreated BM-MSCs) and Ki67 nuclear expression (right; expressed as a percentage of stained B cells). (B) Circos plots showing predicted interactions between BM-MSCs defined as sender cells and FL B cells defined as receiver cells based on the genes enriched in the EV signature and/or TNF/LT signature compared with untreated BM-MSCs and genes enriched in BM FL B cells (left) or LN FL B cells (right) compared with normal centrocytes.