Natural-killer cell amplification for adoptive leukemia relapse immunotherapy: Comparison of three cytokines, IL-2, IL-15, or IL-7 and impact on NKG2D, KIR2DL1, and KIR2DL2 expression

Objective. Natural killer (NK) cells are a lymphocyte subset that, in a hematopoietic stem cell transplantation setting, mediates a graft-vs-leukemia effect without any graft-vs-host disease. We aimed to evaluate an isolation method that can be used with Good Manufacturing Practices grade reagents and to compare three cytokines for expansion in order to design future clinical protocols based on donor NK-cell infusions to cure relapse after allograft. Materials and Methods. NK cells were enriched using a CD3/CD19 depletion method and expanded for 13 days in the presence of 2, 10, and 50 ng/mL interleukin (IL)-2, IL-15, or IL-7. NK-cell cytotoxicity was evaluated after isolation and culture. Expression of NKG2D, KIR2DL2, and KIR2DL1 was monitored during expansion. Results. Highly T- and B-cell depleted NK cells were obtained and enriched 2.6-fold. The optimal cytokine concentration for expansion was 10 ng/mL for IL-2 or 50 ng/mL for IL-15. NK-cell cytotoxicity was significantly improved after an overnight incubation with 10 or 50 ng/mL IL-2 or with 2, 10, or 50 ng/mL IL-15, and after 13 days with 50 ng/mL IL-15. The use of a combination of IL-2 and IL-15 showed no additional benefit and negative results were obtained with IL-7. The three NK cell receptors were significantly upregulated after culture, mainly with IL-2 or IL-15. Conclusion. In our study, 10 ng/mL IL-2 or 50 ng/mL, IL-15 were the optimal concentrations for expansion and were equivalent in significantly enhancing cytotoxicity and modifying NK-cell receptor expression patterns. (C) 2010 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc.