To this aim, IL-6+/+/Pax5+/- mice were randomized to treatment with either immunoglobulin G (IgG) control antibody or an anti-IL-6 antibody, twice a week (10 mg/kg) once the B-ALL disease appeared as a result of natural infection exposure9, as confirmed by the presence of blast cells in the PB (Supplementary Fig. 12A). Here, IL6 is linked to precursor B-cell acute lymphoblastic leukemia.