Decreased Percentages of the Peripheral Blood T-Cell Subsets and the Serum IL-2 Contents in Chickens Fed on Diets Excess in Fluorine

Three hundred 1-day-old Avian broilers were divided into four groups and fed on control diet (F 23 ppm) and high-fluorine diets (400 ppm, high-fluorine group I; 800 ppm, high-fluorine group II; 1,200 ppm, high-fluorine group III) for 42 days (n = 75/group). The percentages of CD (4) (+) and CD (8) (+) T cells were decreased in three high-fluorine groups when compared with those of control group. Meanwhile, the CD (4) (+) /CD (8) (+) ratio were lower in high-fluorine group II at 28 days of age and in high-fluorine group III at 42 days of age than in control group. Also, the serum interleukin-2 (IL-2) contents were decreased in three high-fluorine groups when compared with those of control group. Histopathologically, the thymus became hypocellular in three high-fluorine groups. It was concluded that dietary fluorine excess (400 similar to 1,200 ppm) reduced the percentages of T-lymphocyte subsets and the serum IL-2 contents, and cellular immune function could be affected in chickens.