Release of enzymes by ricin from macrophages and chinese hamster ovary cells in culture

Ricin selectively depletes hepatic Kupffer's cells (macrophages) in mice, and is cytotoxic in vitro to Chinese hamster ovary (CHO) cells, the L 929 (mouse fibroblast) cell line, and rat bone marrow macrophages. Therefore, the toxicity of ricin to the macrophage J-744A. 1 and CHO cell lines was assessed by determining the release of lactate dehydrogenase (LDH), aspartate aminotransfer-ase (AST), and alanine aminotransferase (ALT). Both dose- and time-dependent increases in the release of LDH and AST were observed. In macrophages, concentrations > 10^-9 g ricin/ml inhibited the release of ALT at 48- and 72-h incubation times, whereas ALT release from CHO cells was inhibited by all concentrations of ricin at 24 and 48 h. The results indicate that the release of LDH and AST from macrophage and CHO cell lines may be useful in studies involving the molecular mechanism of toxicity of ricin as well as in assessing the efficacy of potential chemoprotectant agents against ricin.