Modifying effects of the parent and radio-detoxified endotoxins on cell-mediated cytotoxicity and cytokine release.

The cytotoxic effects of the parent and radio-detoxified lipopolysaccharides (LPS and RD-LPS, respectively) were studied at various concentrations (0-50 micrograms/ml) upon cultured human lung carcinoma target cells. There was no significant difference between the effects of the two endotoxins. LPS and RD-LPS at the same concentrations, however, modified the cytolytic activity of human leukocytes (effector cells) and their mediators in different extent. The most remarkable difference was found at 10 micrograms/ml. A much higher cytotoxic activity of effector cells was observed in the case of RD-LPS as compared to the parent LPS. This concentration used for the treatment of X-irradiated and unexposed effector cells at 24 h incubation resulted in elevated release of some cytokines as measured by ELISA. For increasing the natural defence, RD-LPS as immunomodulator may be of practical value.