Effect of bacillus Callmette-Guérin on cytotxicity of cytotoxic T lymphocyte from children with acute lymphoblastic leukemia for killing HL-60 cells in vitro

Objective To study the effect of bacillus Callmette-Guerin(BCG) on cytotxicity of cytotoxic T lymphocyte(CTL) from human peripheral blood of children with acute lymphoblastic leukemia(ALL) for killing HL-60 cells in vitro. Methods The mononuclear cells were isolated from peripheral blood of ALL children and healthy children,and were cultured with RPMI1640,interleukin-2(IL-2),phytohemagglutinin(PHA) and BCG.The growth of CTLs was observed by light microscopy.The proportions of CD3,CD3+CD4+ and CD3+CD8+ were determined by flow cytometry 10 days after culture.MTT method was performed to detect the cytotoxicity of CTLs for killing HL-60 cells. Results Neither the cell number nor the volume of CTLs changed significantly within 2 days of culture,but both began increasing on the 3rd day of culture and reached a peak on the 6-10th days.On the 10th day of culture,the cell number of CTLs in the BCG treatment group was much higher than in the group without BCG treatment.The CD3+CD8+ proportion in the leukemia group was much higher than in the control group.With the effect of BCG,the CD3+CD8+ proportion of the two groups became much higher.The cytotoxicity of CTLs for killing HL-60 cells in the leukemia group was weaker than in the control group. Conclusions BCG along with IL-2 and PHA promotes the proliferation of CTLs and enhances the ability of CTLs in killing HL-60 cells.