IL6 and acquired polycythemia vera: Furthermore, there is a positive correlation between IL-6 protein levels and erythrocytes (r = 0.933, p < 0.01), hemoglobin (r = 0.733, p < 0.05), and hematocrit (r = 0.818, p < 0.05) levels in PV patients heterozygous for JAK2V617F mutation.