CXCL9 and primary myelofibrosis: We have observed a negative correlation between bone marrow fibrosis grade and serum levels of the IFN-γ induced cytokines CXCL9 (an antifibrotic monokine secreted by macrophages) and CXCL10 (another monokine secreted by several cell types including by macrophages, endothelial cells and fibroblasts).