Deoxynivalenol (DON) is the most common fungal contaminant in the human food supply. DON contaminates staple grains (wheat, corn, barley, oats). DON's potential as an agent of biochemical terrorism (it is easy to produce; grain supplies are insecure) also make it a good model for developing environmental human biomonitoring assays. Preliminary data support that this toxin is immunotoxic in vivo and in vitro in concentrations relevant to typical dietary exposures. Research will utilize an assay the PIs have developed to model a simple screening test for environmental immunotoxicants, based on suppression of lymphocyte proliferation in a human cell line. To develop this model, the following unknown effects will be assessed: 1) major DON metabolites on DON immunotoxicity from human plasma samples by synthesizing and testing this metabolite in an assay, and 2) interindividual variation of in human plasma immunotoxic responses due to endogenous or other exogenous factors by assessing the effects of DON-free human plasma assay.