Cytotoxicity of human phagocytes studied in vitro in a novel model based on neutral red absorbtion.

The aim of these investigations was to establish a model for the study of neutrophil (NEU) and monocyte (MO) mediated cytotoxicity (TOX), and to study the protective actions of model protease inhibitor, peroxide scavengers and glucocorticoids in this model. Confluent human fibroblasts were used as target cells (T) and NEU and MO were used as effector cells (E), ratio E/T was 5-10:1. After triggering E with PMA (16-48 nM) for about 24 hours, remaining viable T were detected by incorporation of Neutral Red (NR). Oxidant-induced TOX was performed with H2O2 and t-BuOOH. In contrast to MO TOX, NEU TOX was inhibited by antiprotease and scavengers. On the other hand, MO TOX was inhibited by glucocorticosteroids. This indicates different TOX mechanisms by NEU and MO.