In summary, for newly diagnosed and treatment-naïve DLBCL adults, a higher level of surface TREM2 on circulating M-MDSCs is a poor prognostic factor for both PFS and OS, positively correlated with a higher level of intracellular ARG1 of M-MDSCs, and negatively associated with a lower absolute count of CD8+ T cells in PB. This evidence concerns the gene TREM2 and diffuse large B-cell lymphoma.