Objective: To assess the clinical relevance of chemokine receptor expression on the progression of B-cell chronic lymphocytic leukemia (B-CLL).
Patients and methods: Peripheral blood mononuclear cells from 45 patients with B-CLL were purified and compared with lymph node samples collected from 17 of these patients. Also compared were B cells obtained from peripheral blood samples from 5 healthy controls and B cells from reactive lymph nodes from 3 otherwise healthy persons. The patients were treated at the Mayo Clinic in Rochester, Minn, between January 15,1991, and February 7, 2003. Mononuclear cells were stained by a 2-color (fluorescein isothiocyanate/phycoerythrin) flow cytometric assay using antibodies to the chemokine receptors (CXCR1, CXCR2, CXCR3, CXCR4, CXCR5, CCR2, CCR4, CCR5, CCR6, and CCR7) and also to CD19.
Results: Of the 45 patients in this study, 20 had Rai stage 0 disease, 12 had stage I disease, 3 had stage II disease, 2 had stage III disease, and 8 had stage IV disease. The mean fluorescent intensity (MFI) of the chemokine receptor expression on B-CLL cells was compared with normal controls and was not significantly different, except for an increase in the median expression of CXCR3 (P = .003) and CCR7 (P = .001) on B-CLL cells. We also found a significant increase in the expression of CXCR4 and CCR7 in B-CLL cells from patients with stage IV compared with stage 0 disease (P = .001 and P = .02, respectively). Furthermore, circulating B-CLL cells showed significantly higher expression of CXCR4 and CCR7 when compared with B lymphocytes in lymph nodes (P = .003 and P < .001, respectively).
Conclusion: The expression of CXCR4 and CCR7 on B-CLL cells correlates with Rai stage. Also, these chemokine receptors may be down-regulated once malignant B cells enter the lymph nodes. To our knowledge, this is the first published report that shows the strong association of Rai stage with CXCR4 and CCR7 expression levels in B-CLL cells.