In contrast, in PV and in ET, the levels of many cytokines or receptors correlated positively with the blood counts of leukocytes, neutrophils and monocytes (IL-1β, IL-1Rα, HGF, MIG), platelets (IL-9, IL-17, SDF-1α) or lymphocytes (IL-9). Here, IL9 is linked to essential thrombocythemia.