Experimental Studies On The Effect Of Calcium Ionorphore On Chronic Myelogenous Leukemia Cell Line K562

ObjectivesTo investigate the effect of calcium ionorphore(CI) on B7 costimulatorymolecules of chronic myeloid leukemia cell line K562 and to explore whether theK562 cells can acquire dendritic cell (DC)-like characteristics in vitro with CI.MethodsIn the first part well growing K562 cells were cultured in the RPMI1640medium containing calcium ionorphore(375ng/mL), with K562 cells without CItreatment as control. The cells'viability and number were calculated by TrypanBlue exclusion at 0h,48h,96h. Before and after cultured 96h, B7-1 and B7-2expression was assayed by flow cytometry. The proliferation of allogeneic humanT cells of the two group was detected by MTT colorimetry. In the second partwell growing K562 cells were respectively cultured in the medium containing1000U GM-CSF/ml and 500U IL-4/ml; CI(375ng/ml), 1000U GM-CSF/ml and500U IL-4/ml; only medium. The cellular morphological change was observedunder light microscope. Phenotypic analysis of cells was assayed by flowcytometry. The proliferation of allogeneic human T cells was detected by MTTcolorimetry.ResultsB7 costimulatory molecules were absent or lowly expressed on K562 cells.After 96h of CI treatment, B7 costimulatory molecules of K562 cells weremarkedly up-regulated and activation of allogeneic T cells occurred. No notablemorphological change was found during the culture. K562 cells cultured inmedium with CI grow slower than that without CI. No notable morphologicalchange was found after cultured 96h in medium containing 1000U GM-CSF /mland 500U IL-4/ml. There is no notable difference in the expression rate of CD80,CD83 and CD86 compared with untreated group and cannot markedly stimulatehuman T cells proliferation. After cultured 48h in medium containing 375ng/mlCI, 1000U GM-CSF/ml and 500U IL-4/ml, the cells began to take on manyforms and there were a few prominency on some cells. CD80 and CD86 weremore markedly up-regulated than untreated group, cytokine group and CI groupin 96h and the effect of stimulating allogeneic T cells is more marked than CIgroup. After cultured 24h K562 cells rapidly developed de novo expression ofCD83, a cell surface protein typically expressed during DC activation. CD83expression was essiontially undetectable by 96 hours. There is no any change inthe third group.Conclusions â‘ B7 costimulatory molecules expression on chronic myeloid leukemiacells line K562 surface was defective. These costimulatory molecules on K562cells can be upregulated by calcium ionorphore.â‘¡Calcium ionorphore mayinhibit the growth of K562 cells.â‘¢The combination of GM-CSF and IL-4 cannotinduce the K562 cells acquire dendritic cell (DC)-like characteristics in 96h. CIcombined with GM-CSF and IL-4 can rapidly induce the K562 cells todifferentiate into APCs-like cells. â‘£There may be synergistic effects on CI andcytokines.