An evaluation of abnormal cytokine expression determined that primary myelofibrosis (PMF) patients had significantly increased levels of IL-1 β, IL-1RA, IL-2R, IL-6, IL-8, IL-10, IL-12, IL-13, IL-15, TNF-alpha, G-CSF, IFN-α, MIP-1α, HGF, IFN-γ and VEGF in addition to reduced IFN-γ levels while MIP-1β gave conflicting results. Here, IL6 is linked to primary myelofibrosis.