An optimized MTT bioassay for determination of cytotoxicity of fumonisins in turkey lymphocytes.

In vitro cytotoxicity assays have been performed for detection and quantitation of fumonisins, as possible alternatives for whole animal testing. This study was undertaken to establish optimal in vitro conditions using turkey lymphocytes. Turkey lymphocytes were isolated from peripheral blood by Percoll gradient centrifugation. Cytotoxicity of fumonisin B1 (FB1) and B2 (FB2) was determined by exposing lymphocytes to FB1 or FB2 at concentrations of 0.01-25 micrograms/mL for 24, 48, or 72 h at 39 degrees C. The MTT bioassay was used to measure cell viability and 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 proliferation that was dose-dependent. The 50% inhibitory dose for FB1 and FB2 was 0.4-5 micrograms/mL. Cells exposed to FB1 or FB2 exhibited high levels of cytoplasmic vacuolization and were unable to proliferate, whereas proliferation of control lymphocytes was observed at 48 and 72 h. FB2 was 3- to 4-fold more cytotoxic than FB1.