Effect of ARSI cell line or IL-10 on macrophage polarization

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) is a rare subset of diffuse large B-cell lymphoma (DLBCL) exhibiting genetic features shared with LBCL of immune-privileged sites (notably the MYD88L265P mutation) and enriched in tumor associated macrophages (TAM) expressing M2 markers. Using a unique PCDLBCL-LT cell line (ARSI cell line) developed in our institute, we sought to mechanistically decipher the interplay between lymphoma cells and macrophages. We demonstrate that ARSI cells induce phenotypic, transcriptional and functional changes in macrophages obtained from primary monocytes . These changes do not require cell-cell contact, and proteome analysis of ARSI secretome reveals high concentration of several cytokines and chemokines known to affect macrophages, including IL-10. We then demonstrate that IL-10/IL-10RA interaction blockade inhibits macrophage polarization induced by tumor cells. In conclusion, these results confirm the robustness of this model to study lymphoma cell and macrophage interplays, underline the critical role of IL-10 in lymphoma microenvironment modeling, and may contribute to better define its specificities in an era of rising microenvironment-targeted therapies. Overall design: Monocytes were exposed for 24 hours to one of the following conditions: untreated (control), co-culture with ARSI cell line at 75,000 cells per well, or recombinant human IL-10 at a final concentration of 5 ng/mL. CD14? monocytes were subsequently isolated from all experimental groups using magnetic-activated cell sorting (MACS), according to the manufacturer's instructions, to ensure consistency across conditions. Only samples achieving a minimum post-sort purity of 99.7% were selected for downstream analysis. Purity was assessed by confirming the absence of contaminating ARSI cells, identified by CD20? or CD19? expression. The purified CD14? cells were then cryopreserved