Sulfation of Agrocybe chaxingu polysaccharides can enhance the immune response in broiler chicks

SUMMARY In this study, our objective was to compare the effects of sulfated Agrocybe chaxingu polysaccharide (saCP) and nonsulfated aCP (naCP) on lymphocyte proliferation in vitro and immune-enhancing activity in broiler chicks. In the in vitro test, 3 saCP with different degrees of sulfation—saCP0.83, saCP1.32, and saCP 1.79—were used to study the peripheral lymphocyte proliferation using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay with naCP as the control. On the basis of this test, saCP 1.32 and saCP 1.79 were selected for the in vivo test. In the in vivo test, 300 one-day-old chicks were randomly divided into 5 groups (negative control, vaccine control, naCP, saCP 1.32, and saCP 1.79). Chicks in the vaccine control and aCP groups were vaccinated with newcastle disease (nD) vaccine at 10 d of age, with a booster dose at 21 d of age. at the time of the first vaccination, the chicks in the 3 aCP groups were injected with naCP, saCP 1.32, and saCP 1.79, whereas those in the vaccine control group were injected with 0.5 ml of physiological saline once a day for 3 successive days. In comparison to naCP, saCP 1.32 and saCP 1.79 significantly increased the relative weight of the thymus and spleen at 22 d of age, enhanced serum nD antibody titers at 16, 22, 28, 34, and 42 d of age, and enhanced splenic t- and B-lymphocyte proliferation at 22 and 28 d of age. Furthermore, saCP 1.32 and saCP 1.79 could induce significant augmented levels of interferon-γ and Il-6. Sulfation could enhance both cellular and humoral immunity in broiler chicks on a degrees of sulfation basis. the saCP 1.79 exerted the best efficacy and would be expected to be immunopotentiator molecule during nD vaccination in broilers.