Neutrophils are cytotoxic and growth-inhibiting for neuroblastoma cells with an anti-GD2 antibody but, without cytotoxicity, can be growth-stimulating

Neutrophils and mononuclear cells (MNC) can mediate antibody-dependent cell ular cytotoxicity (ADCC) against cancer cells. To study cytotoxicity and gr owth inhibition of neuroblastoma cells by neutrophils and MNC with chimeric anti-disialoganglioside (GD2) monoclonal antibody (mAb) ch14.18, we develo ped digital image microscopy scanning (DIMSCAN) assays that measure fluores cence of target cells in 96-well plates after 6-18 h (cytotoxicity assay) o r 7 days (growth assay). Neuroblastoma cell lines (GD2-positive: SMS-KCN, S MS-LHN, LA-N-1; GD2-negative: SK-N-SH) were preloaded with calcein acetoxym ethyl ester fbr the cytotoxicity assay or labeled in situ after 7 days of c ulture with fluorescein diacetate in the growth assay. Fluorescence, as qua ntified by DIMSCAN, was correlated with neuroblastoma cell number in both a ssays (100-2000 cells/well). In the cytotoxicity test, both neutrophils and MNC effectively mediated ADCC of GD2-positive but not GD2-negative neurobl astoma cell lines. Cytotoxicity of both neutrophils and MNC increased with effector to target cell (E:T) ratio (5-50:1) and mAb ch.14.18 dose (0.1-10 mu g/ml). ADCC of neutrophils, but not MNC, increased with addition of GM-C SF. Neutrophils, especially with rhGM-CSF, significantly suppressed growth of GD2-positive cell lines at a high E:T ratio (50:1) and mAb dose (10 mu g /ml). Without antibody, neutrophils inhibited growth of one cell line (LAN- 1) but stimulated growth of two others (SMS-KCN, SMS-LHN). If neuroblastoma cells did not express GD2 (SK-N-SH), neutrophils stimulated growth whether or not antibody was present. Neutrophil culture supernatants increased gro wth of SK-N-SH, LA-N-1, and SMS-KCN cells, and MNC culture supernatants inc reased growth of SK-N-SH. In conclusion, neutrophils call mediate cytotoxic ity and growth inhibition with a chimeric anti-GD2 antibody but also can pr omote tumor cell growth if antibody is not present or if GD2 is not express ed.