Augmentation of 17-1A-induced antibody-dependent cellular cytotoxicity by the triple cytokine combination of interferon-alpha, interleukin-2, and interleukin-12

Previously. interferon-alpha (IFN-alpha), interleukin-2 (IL-2), and interle ukin-12 (IL-12) were shown to increase the antibody-dependent cellular cyto toxicity (ADCC) induced by the murine monoclonal antibody 17-1A, which reco gnizes the tumor associated antigen EpCAM. In this study, the authors wante d to determine whether the combination of these three cytokines would yield greater cytotoxicity than the single cytokines. For cytotoxicity assessmen t, a new flow cytometric assay was used that allows the analysis of long-te rm ADCC exerted by macrophages. Peripheral blood mononuclear cells from hea lthy donors were used as effector cells against the colorectal carcinoma ce ll line HT29 at a low effector-to-target ratio of 4.5:1. With this test, th e effectiveness of the combinations IL-2 and IFN-alpha, IL-2 and IL-12, and IL-12 and IFN-alpha were compared with each other. The combinations IL-2 p lus IL-12 and IFN-alpha plus IL-12 were more potent at the concentrations t ested. Furthermore, the triple cytokine combination of IFN-alpha, IL-2, and IL-12 revealed significantly greater ADCC than dual cytokine combinations. Next, CD14(+), CD4(+), and CD4(-) cells were isolated by paramagnetic bead s and magnetic activated cell sorter (MACS) columns. The CD14(+) and CD4(-) cell populations contained the ADCC effecters. The addition of CD4(+) cell s to CD14(+) or CD4(-) cells resulted in augmented ADCC, indicating that co operation between immune cells occurs. These results suggest that multiple cytokine combinations with monoclonal antibodies may be more effective for cancer immunotherapy.