AN OPTIMIZED MTT BIOASSAY FOR DETERMINATION OF CYTOTOXICITY OF FUMONISINS IN TURKEY LYMPHOCYTES

In vitro cytotoxicity assays have been performed for detection and qua ntitation of fumonisins, as possible alternatives for whole animal tes ting. This study was undertaken to establish optimal in vitro conditio ns using turkey lymphocytes. Turkey lymphocytes were isolated from per ipheral blood by Percoll gradient centrifugation. Cytotoxicity of fumo nisin B-1 (FB1) and B-2 (FB2) was determined by exposing lymphocytes t o FB1 or FB2 at concentrations of 0.01-25 mu g/mL for 24, 48, or 72 h at 39 degrees C. The MTT bioassay was used to measure cell viability a nd proliferation. In metabolically active cells, the tetrazolium salt, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], was reduced to MTT formazan. Turkey lymphocytes that had been exposed in vitro to FB1 and FB2 for 48 and 72 h showed inhibition of cell prol iferation that was dose-dependent. The 50% inhibitory dose for FB1 and FB2 was 0.4-5 mu g/mL. Cells exposed to FB1 or FB2 exhibited high lev els of cytoplasmic vacuolization and were unable to proliferate, where as proliferation of control lymphocytes was observed at 48 and 72 h. F B2 was 3- to 4-fold more cytotoxic than FB1.