Despite this variation among patients, all of the cytokines and chemokines analyzed had higher mean levels in PV patients compared to all healthy controls (Table 3A), with IL-2, IL-4, IL-5, IL-9, IL-10, IL-15, IL-22, and IL-23 reaching statistical significance (p-value <0.05) (Table 3B), indicating a general immune activation in patients compared to controls. Here, IL9 is linked to acquired polycythemia vera.