Selenium Rescues Aflatoxin B₁-Inhibited T Cell Subsets and Cytokine Levels in Cecal Tonsil of Chickens

Cecal tonsil is the largest peripheral lymphoid organ of the gut-associated lymphoid tissue executing immune function. To evaluate the protective effect of selenium (Se) on the cecal tonsil of chicken exposed to aflatoxin B₁ (AFB₁), 144 1-day-old healthy Cobb chickens were randomly divided into four groups, and fed with basal diet (control group), 0.6 mg/kg AFB₁ (AFB₁ group), 0.4 mg/kg Se supplement (+Se group), and 0.6 mg/kg AFB₁ + 0.4 mg/kg Se supplement (AFB₁ + Se group) for 21 days, respectively. The results showed that AFB₁ significantly decreased the percentages of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺ T cells, and the CD4⁺/CD8⁺ ratio, and suppressed the expressions of IL-2, IL-4, TNF-α, and IFN-γ mRNA in the cecal tonsil. However, Selenium (Se) supplied in the diets restored the percentages of T cell subsets, the CD4⁺/CD8⁺ ratio, and mRNA expressions of cytokines in the AFB₁ group to be close to those in the control group, and did not exhibit obvious toxicity to the cecal tonsil. These results indicated that Se exerted protective effect against AFB₁ on the functions of cecal tonsil, and also partially uncovered a new role of Se that could protect cecal tonsil of chickens from immunotoxicity of AFB₁.