Since the publication of a novel protocol in 1991, cytokine-induced killer (CIK) cells have shown promising results in the treatment against neoplastic diseases. Despite ongoing preclinical and clinical studies, CIK cell treatment in the context of human monoclonal antibodies targeting tumor-necrosis factor receptors remains overlooked. The present study investigated whether a combination of CIK cells with human monoclonal antibody anti-CD40 and anti-Glucocorticoid-induced TNF-related protein (GITR) would lead to further cytotoxicity against tumor cells expressing CD40 and GITR ligand (L). Therefore, in vitro experiments with human lymphoma cell lines SU-DHL-4 and Daudi (both CD40 positive) and human breast adenocarcinoma MCF-7 (GITRL positive) were performed and the secretion of interferon (IFN)-γ was measured. Three interesting results emerged: i) a combination of CIK cells and anti-CD40 mAb is more effective than CIK cell treatment alone; ii) the use of anti-GITR mAb and CIK cells significantly enhanced the cytotoxicity of CIK cells against MCF-7 compared with single CIK cell treatment and iii) the combination of both antibodies and CIK cells abrogates the anti tumoral effect of CIK cells on all three cell lines. By performing an ELISA for IFN-γ measurement, a lower secretion was observed when anti-CD40 or anti-GITR mAb was added. This outcome indicates that further studies in vitro and in vivo may aid in understanding the synergistic molecular mechanisms of CIK cells, and anti-CD40 and anti-GITR mAb.
Keywords: anti-CD40; anti-GITR; cytokine-induced killer cells; immunotherapy; monoclonal antibody.