Immunostimulatory effects of synthetic bursin (BS) on proliferation of chicken splenic lymphocytes and gene expression of interleukin-2 (IL-2) and interleukin 6 (IL-6) were studied by MTT colorimetry, RIA and semi-quantitative RT-PCR. The results showed that treatment with 0.5 μg/ml, 5 μg/ml or 50 μg/ml of BS for 36 h and then with 10 μg/ml of Concanavalin A (Con A) for 24 h promoted significantly proliferation of chicken splenic lymphocytes. The concentration of IL-6 in the cell supernatant of BS-treated c...