| Objective To investigate the inducibility of K562 cells to killer cells induced by different cytokine cocktails containing rhIL-2.Methods 1.Groups: K562 cells were plated at 5 × 105/ml in 24-well dishes, andwere seperatedly cultured in medium with combinations of cytokines as follows: group A:rhIL-2 was given by different final concentration of 250U/ml, 500U/ml and 1000U/ml to establish group A-250, A-500 and A-1000 respectively; group D: rhIL-2 (1000U/ml) and rhIL-15(100ng/ml); group E:rhIL-2(250U/ml) and rhIL-15 (100ng/ml) and A23187 (250ng/ml).The control group was only given culture medium without cytokines. A23187(250ng/ml) was added to the culture medium of group A from day 10 and day 20 after culture to form group B and group C. Group B and group C both have 3 subgroups because there are 3 subgroups in group A. All cultures were maintained at 37 ℃ in 5% CO2 and humidified atmosphere for 40 days. Every three days,half dose of the inducing agents were added to test wells. 2.Morphology analyses: Cultured cells were observed by phase-contrast microscopy for the change of morphology. 3. Immunophenotype assay: The suface molecule CD3, CD16/56 of induced killer cells were analysed by flow cytometry on the 10th,20th,30th and 40th day after culture, respectively. 4. Immunohistochemistry test: The expression of surface molecule CD56 or CD16 can be identified. 5. Cytotoxic test: The cytotoxic ability of the induced killer cells to target cells was assayed by MTT colorimetry.Results Killer cells can be derived from K562 cells by both single rhIL-2 and cytokine cocktails containing rhIL-2. 1.Morphology: Cells began to display an increase in size since culture for 5 days. 10 days after culture, the inductivity of group A-1000,group D and group E were higher than group A-250 and A-500. The difference was significant (P<0.05). As time went by, all the groups were set up and the inductivity were all increased gradually. After culture for 40 days, the inductivity was 60.83-65.91%...
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