CXCL12 and B-cell chronic lymphocytic leukemia: In addition, CLL nodes have a disrupted architecture featured by the lack of follicles, which are the main source of CXCR5 cognate ligand, the chemokine CXCL13 (133, 134), and the chemokine CXCL12, the ligand of CXCR4, was not found in HEVs from CLL nodes (48).