To evaluate the phenotype of neutrophils, we collected the spleens (SPL) of TCL1 leukemia-bearing mice at two stages of disease development: early (4–10% of leukemic CD5+ CD19+ cells detected in the blood) and late (50–80% of leukemic CD5+ CD19+ cells detected in the blood) (Fig. 1A). Here, CD19 is linked to leukemia.