Short-term exposure to subacute doses of aflatoxin-induced depressed mitogen responses in young mallard ducks

Mallard ducklings were fed diets containing corn naturally contaminated wit h mixed aflatoxins, purified T-2 toxin, or no detectable mycotoxin in two t rials. The aflatoxin level used was 12 ppb in the first trial and 33 ppb in the second. T-2 was added at 2 ppm in both trials. No pathology was associ ated with the aflatoxin used in this study, and T-2-induced lesions were de scribed in a previous publication. The weights of primary (thymus and bursa of Fabricius) and secondary (spleen) lymphoid organs were significantly re duced in the T-2-treated birds. The total number of viable cells recovered from the thymus was significantly reduced in aflatoxin-treated birds. The n umbers of viable cells recovered from thymus, bursa of Fabricius, and splee n were all significantly reduced after treatment with T-2. In each trial, s ignificantly lower mitogenic responses were seen to pokeweed mitogen and co ncanavalin A in birds fed aflatoxin or T-2, representing reduction in both B-cell and T-cell mitogenesis. Birds fed aflatoxin also had significantly r educed Escherichia coli O55 lipopolysaccharide-induced mitogenic responses. These studies indicate that subacute oral exposure to aflatoxin caused a l oss of normal lymphocyte reactivity in mallard ducklings. This finding supp orts the hypothesis that waterfowl that ingest even small quantities of myc otoxin-contaminated waste grain are likely to be more susceptible to bacter ial or viral infections.