OBJECTIVETo study the effect of bacillus Callmette-Guérin (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.

METHODSThe 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.

RESULTSNeither 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.

CONCLUSIONSBCG along with IL-2 and PHA promotes the proliferation of CTLs and enhances the ability of CTLs in killing HL-60 cells.