Dual role of the CXCL12 polymorphism in patients with chronic lymphocytic leukemia

The CXCL12 [chemokine (C-X-C motif) ligand 12] is a member of the CXC family of chemokines and interacts with its CXCR4 receptor. The CXCL12/CXCR4 axis is involved in regulation of proliferation, survival and trafficking of hematopoietic stem cells, including B lymphocytes and disruption within this signaling pathway has been implicated in pathogenesis of chronic lymphocytic leukemia (CLL). The aim of this study was to determine a potential association of the CXCL12 rs1801157 G > A polymorphism with susceptibility to CLL, the disease course and efficacy of therapy. Also, expression of the CD74 and CD38 proteins on B cells was analyzed in relation to clinical parameters and genotyping results. A total of 124 patients with CLL and 75 healthy controls were studied. CXCL12 genotyping was performed using polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) method. The CD74 and CD38 surface expression was determined using flow cytometry. There was a significantly increased frequency of the A allele and AA genotype in CLL patients compared with control group (P < 0.001 in both cases). In addition, the A allele was overrepresented among patients with worse response to therapy in comparison to other genotypes (P < 0.001). On the contrary, patients carrying the A allele displayed lower grade of the disease at diagnosis more frequently than patients homozygous for the G allele (P = 0.037). Moreover, the AA homozygosity correlated with lower CD74 expression on B cells (P = 0.007). In conclusion, data from this study indicate that the CXCL12 rs1801157 G > A polymorphism may affect CLL development, disease progression as well as response to treatment.