Importantly, recent studies have indicated that increasing the number of CD4+ CD25bright FoxP3+ Treg cells, by adoptive transfer or use of the super-agonistic anti-CD28 antibody D665, could suppress antibody production in mouse models of PV, whereas depleting them enhanced the autoantibody production in the same model (49, 50). The gene discussed is FOXP3; the disease is acquired polycythemia vera.