Background
Cytokine-induced killer cells (CIKs) adoptive cell transfer (ACT) is a common malignant tumor treatment method. Interleukin-2 (IL-2) is one of essential cytokines for CIKs culture. In most studies, only the effect of IL-2 concentration on function of CIKs was studied, but the difference between multifarious adding manner of IL-2 was not explored.
Methods
This study established a novel sequential adding manner of IL-2. Different concentration of IL-2 was added in different CIKs induction phase. Then, proliferation ability of CIKs was evaluated using cell proliferation curves, immune phenotype was analyzed by flow cytometry (FCM), IFN-γ secretion ability and cytotoxicity were detected by ELISA Kit and CCK-8 Kit respectively . Multiple comparison tests were conducted between each group to compare function of CIKs in 12 experimental groups.
Results
As the IL-2 concentration increased, the number of CIKs continued to increase in each group, but its function was not positively related with its number: CD3+ CD56+ subpopulation ratio, INF-γ secretion ability and cytotoxicity presented irregular changes. During quiescent phase and logarithmic growth phase, adding 300 and 1000 U/mL IL-2 respectively could obtain amounts of powerful CIKs (CD3+ CD56+ subpopulation ratio: 40.9%, INF-γ secretion ability: 542pg/mL, cytotoxicity: 40:1, 74.22) .
Conclusions
Different concentration of IL-2 had a greater influence on biological function of CIKs in different growth phase, it was better to add IL-2 sequentially in quiescent phase and exponential growth phase of CIKs.