RESUMO
<p><b>OBJECTIVE</b>To study the expression of CXCR4 in acute leukemic cells and its clinical significance.</p><p><b>METHOD</b>Bone marrow samples from 73 acute leukemia patients and leukemic cell lines were investigated by flow cytometry (FCM), the expression of SDF-1 in human marrow stromal cells and meninges were studied by using reverse transcription polymerase chain reaction (RT-PCR). Adhesion, migration and invasion of U937, NB4 and K562 cells were studied in vitro.</p><p><b>RESULTS</b>The expression rates of CXCR4 in ALL and AML patients was 65.6% and 17.1%, respectively. And it was 0.2%, 41.0% and 52.0% in K562, U937 and NB4 cells, respectively. The extramedullary infiltration rates were 61.9% and 18.2% for CXCR4 positive and negative groups of ALL, respectively (P < 0.05); while in AML, the number of peripheral white blood cells in CXCR4 positive group was lower than that in CXCR4 negative group (P < 0.05). SDF-1alpha could enhance the adhesion, migration and invasion capacity of leukemic cells in vitro.</p><p><b>CONCLUSION</b>Overexpression of CXCR4 in AL cells might be the molecular mechanism of extramedullary infiltration in leukemia.</p>