Some years later, in addition to the correlation of increased levels of IL-6 and TNF-α in the pathogenesis of PV, higher levels of IL-8, IL1-β, and IL-15 were also found in the serum of PV patients, whereas the levels of IL-1β and IL-22 were lower than in controls [9–15]. This evidence concerns the gene CXCL8 and acquired polycythemia vera.