It is assumed that oxidative damage caused by
reactive oxygen species (ROS) from activated neutrophil granulocytes may contribute to pathology of
tumors. ROS are crucial in neutrophil-mediated
tumor cell lysis. The present study is focused on the oxidative burst and antitumorous activities of neutrophils when challenged with Walker
carcinoma W256. Survival and
tumor growth dynamics were monitored in vivo, while
tumor cell proliferation when mixed with neutrophils was studied in vitro together with the generation/release of neutrophil respiratory burst products, primarily 1O2. Neutrophils were collected upon
Sephadex injection. The survival of
Sephadex injected animals was slightly improved, while their
tumors grew less than in controls. The presence of
tumor cells in vitro activated neutrophils to produce
singlet oxygen similar to
phorbol ester. Neutrophils from
Sephadex-bearing animals diminished
tumor cell proliferation in vitro (measured by 3H-TdR incorporation), while neutrophils from
Sephadex and the
tumor-bearing animals did not show such activity in vitro. Our results confirm that in the case of rapidly growing
tumors such as murine W256
carcinoma neutrophils have antitumorous effects in the early phase of
tumor development.