ARG1 and diffuse large B-cell lymphoma: Following the flow cytometry analysis, frequencies of M-MDSCs were significantly increased in lymphoma patients compared to healthy individuals, and the elevated M-MDSC levels correlated with an advanced stage of disease (III/IV), aggressive histology (DLBCL vs. other low-grade B-NHLs), and relapsed/refractory disease, which was also correlated with increased plasma levels of Arg-1.