ARG1 and B-cell non-Hodgkin lymphoma: To validate the causal relationship between TREM2 on M-MDSCs cell surface, ARG1 from M-MDSCs, and CD8+ T cells, we adopted an in-vitro MDSCs system (Fig. 5A) [29, 30] by utilizing primary BM cells derived from B6 mice under the consideration that (1) Trem2 KO mice were constructed on the B6 mouse strain and (2) currently there are no commercially available B-cell lymphoma cell lines that originate from B6 mice.