Previous studies have detected Dsg3-specific T cells in healthy individuals carrying PV-associated HLA class II alleles (198, 199), However, these genetically susceptible individuals do not manifest PV phenotypes, which is attributed to the presence of IL-10- and TGF-β-secreting Dsg-3-specific Treg cells in this population—a cell type rarely found in PV patients (200). Here, IL10 is linked to acquired polycythemia vera.