Inhibitory effects of dietary aflatoxin B1 on cytokines expression and T-cell subsets in the cecal tonsil of broiler chickens

Aflatoxin B1 (AFB1) is the most toxic form among the mycotoxins. Cytokines are important mediators of the immune system. T-cell subsets play a crucial role in cell-mediated immunity. The aim of present study was to evaluate the effects of dietary AFB1 on the cytokines expression and T-cell subsets in the cecal tonsil of broiler chickens throughout a 21-day experimental period. One hundred and fifty six one-day-old broiler chickens were randomly divided into control group (0 mg AFB1/kg feed) and AFB1 group (0.6 mg pure AFB1/kg feed). At 7, 14 and 21 days of age, the levels of seven cytokines (IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ and TNF-α) mRNA expression as well as the proportions of T-cell subsets (CD3+, CD3+CD4+, CD3+CD8+) by qRT-PCR and flow cytometry methods were assessed in the cecal tonsils. The levels of the seven cytokines mRNA expression and the percentages of T-cell subsets significantly decreased at 14 and 21 days of age in the AFB1 group compared with the control group. However, the CD4+/CD8+ ratio was not significantly changed. These results demonstrate that 0.6 mg/kg AFB1 dietary exposure reduced the levels of cytokines mRNA expression and the percentages of T-cell subsets in the cecal tonsils of broiler chickens, suggesting that the cell-mediated immunity of cecal tonsils might be impaired in broilers