While Prabhala et al. [2] showed an increase in CD4+ CD25+ in peripheral blood and BM of monoclonal gammopathy of undetermined significance (MGUS) and MM patients when compared with controls, they also found that Treg cells—evaluated by FOXP3 expression—are significantly decreased in number and function in patients with MGUS and MM compared with healthy donors. Here, FOXP3 is linked to monoclonal gammopathy.