Cytotoxic Capacity of IL-15-Stimulated Cytokine-Induced Killer Cells Against Human Acute Myeloid Leukemia and Rhabdomyosarcoma in Humanized Preclinical Mouse Models

Abstract

Allogeneic stem cell transplantation (allo-SCT) has become an important treatment modality for patients with high-risk acute myeloid leukemia (AML) and is also under investigation for soft tissue sarcomas. The therapeutic success is still limited by minimal residual disease (MRD) status ultimately leading to patients’ relapse. Adoptive donor lymphocyte infusions based on MRD status using IL-15-expanded cytokine-induced killer (CIK) cells may prevent relapse without causing graft-versus-host-disease (GvHD). To generate preclinical data we developed mouse models to study anti-leukemic- and anti-tumor-potential of CIK cells in vivo. Immunodeficient mice (NOD/SCID/IL-2Rγc−, NSG) were injected intravenously with human leukemic cell lines THP-1, SH-2 and with human rhabdomyosarcoma (RMS) cell lines RH41 and RH30 at minimal doses required for leukemia or tumor engraftment. Mice transplanted with THP-1 or RH41 cells were randomly assigned for analysis of CIK cell treatment. Organs of mice were analyzed by flow cytometry as well as quantitative polymerase chain reaction for engraftment of malignant cells and CIK cells. Potential of CIK cells to induce GvHD was determined by histological analysis. Tissues of the highest degree of THP-1 cell expansion included bone marrow followed by liver, lung, spleen, peripheral blood (PB), and brain. RH30 and RH41 engraftment mainly took place in liver and lung, but was also detectable in spleen and PB. In spite of delayed CIK cell expansion compared with malignant cells, CIK cells injected at equal amounts were sufficient for significant reduction of RH41 cells, whereas against fast-expanding THP-1 cells 250 times more CIK than THP-1 cells were needed to achieve comparable results. Our preclinical in vivo mouse models showed a reliable 100% engraftment of malignant cells which is essential for analysis of anti-cancer therapy. Furthermore our data demonstrated that IL-15-activated CIK cells have potent cytotoxic capacity against AML and RMS cells without causing GvHD.

Cytokine-induced killer cells promote antitumor immunity

“…Trafficking of CIK cells is hard to investigate in cancer patients. One approach to further study the trafficking is to use various humanized mouse models [73]. In vivo trafficking can also be studied by tracking genetically engineered T cells upon infusion [74].…”

IL-15 Improves the Cytotoxicity of Cytokine-induced Killer Cells Against Leukemia Cells by Upregulating CD3+CD56+ Cells and Downregulating Regulatory T Cells As Well As IL-35

“…Enhancing CIK cells function in vivo through the administration of supportive cytokines therapy, such as IL-2, IL-12, and IFN-g, can improve the cytotoxicity but has been associated with substantial side effects. 10,11 The data showed that IL-15-stimulated CIK cells (IL-15-CIK cells) have an increased antitumor potential in vitro compared with IL-2-stimulated CIK cells (IL-2-CIK cells). 9 Conventional CIK cells are usually generated from peripheral blood mononuclear cells (PBMCs) of healthy donors or tumor patients, with IL-2, IFN-g, IL-1, and anti-CD3 monoclonal antibody.…”

NaHCO3 enhances the antitumor activities of cytokine-induced killer cells against hepatocellular carcinoma HepG2 cells

“…Peripheral blood mononuclear cells (PBMCs) were isolated from peripheral blood by standard Ficoll separation, as previously described (5). Human peripheral blood samples were obtained with full informed consent from patients with HCC.…”

“…Cytokine-induced killer (CIK) cell therapy is currently one of the most commonly used immunotherapies (3). In order to improve the efficacy of CIK cell therapy, numerous strategies, including gene transfection (4), stimulation with certain growth factors (5), pretreatment with antitumor drugs (6), or combination with genetically modified dendritic cells (7), have been attempted in practice. However, a number of clinical trials of CIK cell therapies failed to demonstrate any noticeable improvement over other therapeutic regimens, neither in terms of HCC control rates nor long-term survival rates (8), suggesting that other factors, such as the environment where CIK cells are functioning, should also be considered for immunotherapies.…”