Generation of cytokine-induced killer cells using exogenous in interleukin-2, -7 or -12

Immunologic effector cells termed cytokine-induced killer (CIK) cells are g enerated in vitro from peripheral blood lymphocytes by addition of interfer on-gamma, interleukin (IL)-2, IL-1 and an antibody against CB3. CIK cells h ave been shown to eradicate established tumors in a SCID mouse/human lympho ma model. CIK cells are dependent on exogenous cytokines such as IL-2, IL-7 , or IL-12. We studied the effect of these cytokines in detail. Cellular pr oliferation was analyzed using an MTT proliferation assay, surface antigen expression via flow cytometry, cytotoxic activity using an LDH release assa y, and apoptosis via flow cytometric analysis. IL-2, IL-7 and IL-12 led to significant growth of lymphocytes. Cells grown in IL-2 and IL-7 showed high er proliferation rates than cells grown in IL-12 according to the MTT assay . Concerning surface antigen expression, exogenous IL-7 led to a decrease i n IL-7 receptor expression (4.8% from 60.4%) and exogenous IL-2 to a decrea se in IL-2 receptor expression (61.2% from 73.2%). CD28 expression was high er in cells grown in IL-7 (77.3%) than in cells grown in IL-2 (62.5%). IL-1 2 led to a decrease in ICAM-1 adhesion molecule expression (57.7% from 76.7 %) and an increase in CD56 expression compared with exogenous IL-7. IL-7 le d to higher number of CD4-positive cells than IL-2 (53.0% vs 49.5%). No sig nificant difference was found between IL-2, IL-7 and IL-12 in cytotoxic act ivity measured in an LDH release assay. Small amounts of apoptotic cells we re found with all cytokines. However, the percentage of necrotic cells was higher with exogenous IL-12 than with IL-2 or IL-7. In summary, CIK cells c an be generated using exogenous IL-2, IL-7 or IL-12. No difference in cytot oxic activity was found. However, significant differences were found in cel l proliferation rates, antigen expression and percentage of necrotic cells.