Of note, in these patients, the percentage of CXCL8-secreting CD34+ cells correlated with the degree of reticulin fibrosis and leukocytosis, hinting that CXCL8 secretion may serve as a biomarker for the presence of significant bone marrow fibrosis and a more aggressive disease. This evidence concerns the gene CXCL8 and primary myelofibrosis.