[Comparative study on the lysis of leukemia cells by IL-2 activated bone marrow and cord blood].

OBJECTIVE

To explore the antitumor activity of IL-2 activated bone marrow (ABM) and cord blood (ACB) mononuclear cells.

METHODS

The antitumor activity of ABM and ACB mononuclear cells to the K562 (NK sensitive) and HL-60 (NK resistant) cells was studied by 3H-TdR release assay and semisolid culture method. The progenitor cell activity (PCA) of ABM and ACB was also assayed.

RESULTS

After coculturing for 24 hrs with IL-2, the tumor-killing activities of ABM to K562 cells and to HL-60 cells were identical, while the activity of ACB to K562 cells was higher than that to HL-60 cells. After 72 hr coculturing, the activities of ABM to K562 and HL-60 cells were still higher than that of ACB. The optimum conditions for the activation of ABM and ACB were 1000U/ml IL-2, 1 x 10(6)/ml cells, 100 : 1 effector to target ratio and 72 hr culturing. PCA was not affected after IL-2 activation, while the immunophenotypic markers changed greatly. TNFalpha and IL-6 were detectable after culturing for 24 hrs, and went higher at 72 hrs. Large granular lymphocytes were generated both in cord blood and bone marrow after 24 hr culturing with IL-2.

CONCLUSION

Both bone marrow and cord blood could be activated by IL-2 and gained cytotoxic effects, but the cytotoxicity of ACB was slightly lower than that of ABM under the same culturing condition. The mechanism of cytotoxicity might be cell mediated cytotoxicity and releasing of cytokines such as TNFalpha and IL-6.