The effects of four mycotoxins on the mitogen stimulated proliferation of bovine peripheral blood mononuclear cells in vitro

The effects of four mycotoxins, T-2 toxin, deoxynivalenol (DON), ochratoxin A (OTA) and fumonisin B-1 (FB1) on the response of bovine peripheral blood mononuclear cells (PBM) in vitro to the mitogens concanavalin A (Con A), phytohaemagglutinin A (PHA) and pokeweed mitogen (PWM) were assayed after 4 days' incubation using H-3-thymidine uptake and the MTT bioassay. The concentrations of mycotoxin required to reduce the proliferative response of PBM by 50% for Con A, PHA and PWM as measured by 3H-thymidine incorporation was for T-2 toxin 0.30, 0.40 and 0.18 ng ml(-1); for DON 0.07, 0.09 and 0.04 mu g ml(-1); for OTA 0.10, 0.20 and 0.15 mu g ml(-1), and for FB1 35, 18 and 11 mu g ml(-1) respectively. The concentrations of mycotoxin required to reduce the proliferative response of PBM by 50% for Con A, PHA and PWM as measured by the MTT bioassay were for T-2 toxin 2.0, 2.0 and 1.0 mg ml(-1); for DON 0.70, 0.50 and 0.50 mu g ml(-1); OTA 1.5, 1.5 and 1.5 mu g ml(-1) and FB1 >50, >50 and 20 mu g ml(-1) respectively. Further cytotoxicity assays including the LDH bioassay and Trypan blue exclusion were performed only on Con A stimulated PBM cells after 72 h incubation. With the LDH-bioassay the 50% inhibition levels were T-2 toxin 0.3 ng ml(-1), DON 0.4 mu g ml(-1), OTA 1.4 mu g ml(-1) and FB1 3.5 mu g ml(-1); for Trypan blue uptake the 50% inhibition levels were T-2 toxin 5 ng ml(-1), DON 2.3 mu g ml(-1) and OTA 4 mu g ml(-1) respectively.