Macrophages and cultured human monocytes can mediate efficient antibody-dependent cytotoxicity (ADCC) against human tumor cells using monoclonal antibodies (mAbs). The mechanism of this killing is usually assumed to involve secreted factors (reactive oxygen intermediates, tumor necrosis factor, or other cytotoxic factors) leading to target cell lysis. In this study, we present evidence that phagocytosis of intact target cells is the principal mechanism of antitumor cytotoxicity in our in vitro model of ADCC by cultured monocytes. Human monocytes cultured in recombinant human macrophage colony-stimulating factor ingested up to 100% of fluorochrome-labeled melanoma and neuroblastoma target cells, in the presence of an appropriate antitumor mAb. Electron microscopy demonstrated phagocytosis of intact tumor cells by cultured monocytes during ADCC. All of the radionuclide in radiolabeled target cells was taken up by monocytes during phagocytosis. By preventing the release of radioisotope tracers, phagocytosis thus prevents the detection of this very efficient form of cytotoxicity by most conventional assays.
Article|
July 01 1990
Phagocytosis of tumor cells by human monocytes cultured in recombinant macrophage colony-stimulating factor.
D H Munn,
D H Munn
Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
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N K Cheung
N K Cheung
Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
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D H Munn
Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
N K Cheung
Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Online ISSN: 1540-9538
Print ISSN: 0022-1007
J Exp Med (1990) 172 (1): 231–237.
Citation
D H Munn, N K Cheung; Phagocytosis of tumor cells by human monocytes cultured in recombinant macrophage colony-stimulating factor.. J Exp Med 1 July 1990; 172 (1): 231–237. doi: https://doi.org/10.1084/jem.172.1.231
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