[System Amplifying NK Cells Using Mononuclear Cell Culture].

OBJECTIVE: To develop an easy method to amplify natural killer (NK) cells by using mononuclear cells in vitro, so as to lay the basis for NK cell therapy.

METHODS: Umbilical cord blood from 3 healthy full-term pregnant women was collected, and the peripheral blood mononuclear cells (PBMNC) were harvested by density gradient centrifugation. Each sample of PBMNC was divided into 3 groups: CD16mAb, CD3 mAb and CD16mAb+CD3mAb- groups. The culture flasks were pre-coated with CD16, CD3 or CD3 plus CD16 mAb. The PBMNCs were cultured in serum-free media containing autologous plasma, recombinant human IL-2, IL-15 and IL-21 for 14 days under the same conditions. The total viable cell count was calculated. Flow cytometry was used to determine the ratio of CD56+ CD3- cells, MTT assay was used to measure the killing rate of NK cells under different effector/target ratio, by using the K562 cells as the target cells.

RESULTS: After 14 days of culture, the total cell numbers of CD16mAb, CD3mAb and CD16mAb +CD3mAb groups increased by 45.71±5.54, 87.41±19.77 and 4.88±51.84 times, respectively, and those of CD3mAb group were significantly higher than the other 2 groups (P<0.05). The ratio of CD56+ CD3- cells before culture was 0.1663±0.0201, which was 0.8167±0.0500, 0.8077±0.0589 and 0.8077±0.0273 after incubation with CD16mAb, CD3mAb and CD16mAb +CD3mAb for 14 days, respectively (P>0.05). MTT test showed that the killing efficiencies were not significantly different among the 3 groups when the effector/target ratios were 1:1, 5:1 and 10:1 (P>0.05).

CONCLUSION: By incubation with anti-CD3 monoclonal antibody, IL-2, IL-15 and IL-21, the highly purified NK cells can be obtained from mononucleated cells, thus providing a simple method for NK cell therapy.