The combination of interleukin-2 and interferon effectively augments the antibody-dependent cellular cytotoxicity of monoclonal antibodies 17-1A and BR55-2 against the colorectal carcinoma cell line HT29

Abstract

 Monoclonal antibodies (mAb) are promising substances for the treatment of colorectal carcinoma, but the efficiency of this therapy still needs further improvement. We used a flow-cytometric cytotoxicity test to determine the efficacy of the cytokines interferon α (IFNα) and γ (IFNγ), interleukin-2 (IL-2), macrophage-colony-stimulating factor (M-CSF), granulocyte/macrophage-CSF (GM-CSF) and tumor necrosis factor α (TNFα) in enhancing the antibody-dependent cellular cytoxicity (ADCC) of the mAb 17-1A and the mAb BR55-2 against the colorectal carcinoma cell line HT29. In experiments performed at an effector to target ratio of 9:1, with peripheral blood mononuclear cells from five healthy volunteers as effector cells, we found that IFNα, IFNγ and IL-2 significantly augmented the ADCC of both mAb at concentrations between 3 ng/ml and 30 ng/ml. The other three cytokines were not effective. In further experiments we examined combinations of the three effective cytokines in different concentrations. The combination of IFNα and IL-2 proved to be optimal in enhancing ADCC of both mAb. Thus, the examination of ADCC by flow cytometry may reveal potentially useful combinations of cytokines and mAb for the treatment of colorectal carcinoma.