Objective: To explore the expansion method of high purity NK cells from human peripheral blood and explore the changes in biological functions of NK cells after ex vivo expansion.
Methods: NK cells were isolated from peripheral blood mononuclear cells (PBMNCs) by using miniMACS (Magnetic cell-selection) and NK Cell Isolation Kit II, and cultured in SCEM (Stemline Hematopoietic Stem Cell Expansion Medium, Sigma) supplemented with 10% human AB serum and different combinations of interleukin (IL)-2 and/or IL-12, IL-15 for 15 days. Cultures were semi-exchanged with fresh media and cytokines every 3 days. Evaluation for cell expansion, phenotype, perforin and granzyme B mRNA expressions, and IFN-gamma secretion before and after the culture period.
Results: CD3(-) CD56(+) cells concentration increased from (11.2 +/- 5.2)% to (94.2 +/- 3.5)%. In group IL-2 + IL-15 and IL-2 + IL-15 + IL-12 group, cells were expanded 50.5 +/- 4.3 and 52.3 +/- 6.7 - fold, respectively, being significantly higher than that in other three groups [(15.4 +/- 1.1 fold in IL-2 group, 19.9 +/- 3.9 fold in IL-2 + IL-12 group, 6.1 +/- 1.0 fold in control group)] (P<0.01), but no significant difference between each other (P>0.05). The purity of CD3(-) CD56(+) NK cells was over 94% in all groups except the control. The perforin and granzyme B mRNA expressions of expanded NK cells in four experimental groups were significantly higher than those of before expansion (P<0.01) and the expressions in IL-2 + IL-15 and in IL-2 + IL-12 + IL-15 group were significant higher than in other three groups (P<0.01) while no significant difference between each other (P>0.05). IFN-gamma levels in the supernatants of four experiment groups were significantly higher than that in control group (P<0.01) and its levels order was IL-2 + IL-15 + IL-12 group > IL-2 + IL-12 group > IL-2 + IL-15 group > IL-2 group (P<0.01).
Conclusion: High purity NK cells isolated by negative selection using miniMACS can be efficiently expanded with IL-2 + IL-15, and their biological functions were enhanced.