EXAMINATION OF THE TOXICITY OF SEVERAL PROTEIN TOXINS OF PLANT-ORIGINUSING BOVINE PULMONARY ENDOTHELIAL-CELLS

The bovine pulmonary endothelial (BPE) cell line was examined as a mod el to study the toxicity of ricin and abrin toxins currently under inv estigation. The BPE cell line was examined because ricin has been show n to bind to endothelial cells. Cell viability was assessed using seve ral different biochemical parameters including growth (DNA by binding of gentian violet stain), mitochondrial function (succinate dehydrogen ase activity) using MTT and lysosomal integrity (neutral red retention assay). In order to compare toxicities and investigate potential prot ective compounds, concentrations of toxins causing death of 50% and 70 % of the (control) cell population (LC(50) and LC(70), respectively) w ere determined. It is concluded that while ricin and abrin share a com mon mechanism of action ricin is slightly less toxic than abrin. BPE c ells are a good model for future mechanistic studies and particularly for initial phase screening of potentially therapeutic compounds. Carb ohydrates were used in an attempt to examine which receptor types were involved in the binding and uptake of ricin and abrin by the cell lin e. It was found that only high concentrations of galactose prevented l ethality while mannose apparently had no effect. Furthermore, the mola r excess of carbohydrate to toxin required in order to achieve protect ion indicated that this would be an impractical approach to adopt in v ivo.