CXCL12 and B-cell chronic lymphocytic leukemia: T cells from CLL patients and healthy donors have comparable expression of CCR7 and CXCR4 surface levels (52, 115), although CLL-associated T cells are less responsive to CXCL12, CCL21 and CCL19, except in T cells from patients with ZAP-70-expressing leukemic clones where migratory responses where similar to normal T cells (115).