Relationship between antibody-dependent tumour cell lysis and primary granule exocytosis by human neutrophils

Neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) against Raji target cells and neutrophil degranulation during the ADCC process were evaluated in the presence and in the absence of different agents able to interfere with the neutrophil release of granule components (anion channel blockers, colchicine, isoproterenol, dimethylxanthine, cAMP). When used at concentrations incapable of preventing the target cell recognition by neutrophils, the majority of these agents inhibited both the ADCC and the release of myeloperoxidase (MPO, primary granule marker) and lysozyme (LZM, primary and secondary granule marker). The inhibition of the ADCC correlated strictly with the inhibition of the MPO release. Thus, the results are consistent with the hypothesis that neutrophil primary granules play a major role in the cytolytic process.