CXCR5 and B-cell chronic lymphocytic leukemia: This idea is supported by the findings of others who observed that, in the case of chronic lymphatic leukaemia, CXCR5 and its ligand were overexpressed in malignant B cells but that CXCR5 was downregulated after stimulation with soluble CXCL13 (Burkle et al, 2007).