Objective:To investigate the expression of CXCR, on HL-60 cell line and the proliferation, apoptosis of HL-60 cell line cocultured with bone marrow stromal cells, so as to assess the possibility of 12G5. an anti-CXCR4 monoclonal antibody, in eradicating the minimal residual disease. Methods:The activity of SDF-1 was inhibited by 10μg/ml 12G5. After treatment with 12G5. the status of adhesion was observed, and the adhesion rates, apoptosis and cell cycles were detected after 24 h of treatment. Cell growth rates were measured by trypan blue exclusion. Cell growth curve was plotted, and the expression of PCNA and apoptosis related protein including PCNA, Bcl-2 and Fas were detected with immunohis-tochemical technique. Results :(1) There was middling degree expression of CXCR4 on HL-60 membrane. From 0 h to 6 h, as the time of 12G5 incubation along, the expression of CXCR4 decreased gradually. (2) After treatment for 24 h, the adhesion rates in the experiment group and the control were (39. 4±7. 9)% and (51. 4±5. 9)%, respectively. (3)After treatment for 24 h, the percentage of HL-60 cells in G0/G1 phase were (55. 21±4. 9)%, and that in S phase and G2/M phase were (30. 40±4. 1)% and (14. 39±5.2)%, respectively, with the corresponding proportions being (44. 67±2. 2) % , (45. 30±3. 7)% . and (10. 03±2. 6)% in the control. (4) The percentage of apoptotic HL-60 cells was (8. 95±1. 7)% in the experiment group, compared to (3. 97±2. 4)% in the control. (5)The survival rates of HL-60 cells decreased markedly at 48 h to 96 h, and the proliferation slowed down at this time duration. (6)The expression of PCNA and Bcl-2 down-regulated significantly, but the Fas protein expression was up-regulated. Conclusion :12G5 could inhibit the capability of adhesion and proliferation of HL-60 cells and it can induce more cells to enter G0/G1 phase and promote apoptosis. It may be helpful by inhibiting the bioactivity of SDF-1 with 12G5 in the therapy of marrow residual disease. Objective: To investigate the expression of CXCR, on HL-60 cell line and the proliferation, apoptosis of HL-60 cell line cocultured with bone marrow stromal cells, so as to assess the possibility of 12G5. An anti-CXCR4 monoclonal antibody, in Methods: The activity of SDF-1 was inhibited by 10 μg / ml 12G5. After treatment with 12G5. the status of adhesion was observed, and the adhesion rates, apoptosis and cell cycles were detected after 24 h of treatment . Cell growth rates were measured by trypan blue exclusion. Cell growth curve was plotted, and the expression of PCNA and apoptosis related protein including PCNA, Bcl-2 and Fas were detected with immunohis-tochemical technique. Results: (1) There was middling degree of CXCR4 on HL-60 membrane. From 0 h to 6 h, as the time of 12G5 incubation along, the expression of CXCR4 decreased gradually. (2) After treatment for 24 h, the adhesion rates in the experiment group and the control were (3 (4) After treatment for 24 h, the percentage of HL-60 cells in G0 / G1 phase were (55.21 ± 9)% and (51.4 ± 5.9)%, respectively 40 ± 4. 1% 和 (14.39 ± 5.2)%, respectively, with the corresponding proportions being (44. 67 ± 2%), and that in S phase and G2 / (4) The percentage of apoptotic HL-60 cells was (8. 95 ± 1. 2)%, (45.3 ± 3. 7)%. (5) The survival rates of HL-60 cells were markedly at 48 h to 96 h, and the proliferation slowed down at (6) The expression of PCNA and Bcl-2 down-regulated significantly, but the Fas protein expression was up-regulated. Conclusion: 12G5 could inhibit the capability of adhesion and proliferation of HL-60 cells and it can induce more cells to enter G0 / G1 phase and promote apoptosis. It may be helpful by inhibiting the bioactivity of SDF-1 with 12G5 in the therapy of marrow residual disease.