Enhancing Cytotoxicity of Cytokine-Induced Killer (CIK) Cells against Refractory Leukemia

Haploidentical stem cell transplantation (SCT) has become an important treatment modality for patients with high-risk acute leukemia. Nevertheless, the therapeutic success is still mainly affected by relapse. Cytokine-induced killer (CIK) cells may serve as an alternative approach to adoptive donor lymphocyte infusions (DLI) in cases of impending relapse. In this study, we investigated the feasibility of generating CIK cells for adoptive immunotherapy after haploidentical transplantation. We analyzed the cytotoxic potential of CIK cells against CML and AML as well as T- and B-ALL cell lines. Notably, cytotoxic activity against B- ALL cell line was reduced. Comparable results were obtained against Bcl-2 transfected T-ALL cell line Jurkat. But, depletion of regulatory T cells (Treg) or IL-15 stimulation of CIK cells increased CIK cell-mediated cytotoxicity against B-ALL cell line Tanoue. Irrespective of the mode of CIK cell expansion, the alloreactive potential against allogeneic PBMCs remained low. Therefore, these in vitro expanded CIK cells may be a useful therapeutic option, in case of an impending or open leukemic relapse following haploidentical transplantation.