Impact of stromal cells on malignant B cells in lymphoma-invaded BM. (A) Circos plot showing predicted interactions between ligands from LepR⁺ MSCs and receptors from DOHH2 recovered from the grafted mouse at day 40. MSC_Gr.Late were defined as senders, and DOHH2 D40 as receivers. (B) Heat map representation of ligand activity of MSC_Gr.Late vs DOHH2 D40 cells. Colors correspond to Pearson coefficient quantifying ligand activities and text to P values assessed by random permutation. (C) Diagram of significative bidirectional interactions detected, by CellPhoneDB, between ligands from MSC_Gr.Late and receptors from human primary FL B cells,³³ and observed in >8 of 20 patients with FL. Interactions predicted in panel A are highlighted in red. (D) Quantification by Luminex of matrix proteins and cytokines in the BM plasma from patients with FL (n = 11; except for TGFβ1, n = 13) collected at diagnosis and after 12 months of treatment. Blue dots represent patients with FL and green dotted line represent HD median level. Statistical significance was determined using the Mann-Whitney nonparametric U test. ∗P < .05; ∗∗P < .01. ns, nonsignificant.