These data suggest, in view of the increased CX3CL1 levels observed in the BM plasma of B-ALL patients [70], that CX3CL1/CX3CR1 should be investigated as a possible chemokine axis guiding the recruitment not only of NC monocytes (see above), but also of MDSCs in the leukemic BM niche. The gene discussed is CX3CR1; the disease is precursor B-cell acute lymphoblastic leukemia.