Immunopotentiating effects of four Chinese herbal polysaccharides administered at vaccination in chickens.

This study was conducted to evaluate the effects of 4 Chinese herbal polysaccharides on the production of serum antibodies and the proliferation of peripheral T lymphocytes, including subpopulations in vaccinated chickens. A total of 450 chickens were randomly assigned to 9 groups at 14 d of age and vaccinated first with live Newcastle disease (ND)-infectious bronchitis virus vaccine, and second with ND-infectious bronchitis oil adjuvant vaccine at 28 d of age. At the same time as the first vaccination, the chickens in groups 1 to 8 were intramuscularly injected with 4 polysaccharides at high and low dosages, respectively, once a day for 3 successive days starting on the day of the first vaccination. Group 9 (control group) was injected in the same manner with saline instead of a polysaccharide. On d 7, 14, 21, 28, 35, 42, and 49 after the first vaccination, the temporal changes in serum ND hemagglutination inhibition antibody titer were determined by the micromethod. On d 10, 20, 30, 40, and 50 after the first vaccination, the proliferation of peripheral blood mononuclear cells in response to concanavalin A stimulation as well as the proportions of CD3(+), CD4(+), and CD8(+) peripheral blood mononuclear cells were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method and flow cytometry, respectively. The results showed that astragalus polysaccharide and isatis root polysaccharide at low dosages, and achyranthes root polysaccharide and Chinese yam polysaccharide at high dosages significantly enhanced the ND antibody titers, concanavalin A-induced proliferation of peripheral blood lymphocytes, and ratio of CD4(+) to CD8(+) (P <0.05). Collectively, these findings indicate that the 4 polysaccharides possess significant immune-enhancing properties in chickens. This finding may have direct application in vaccine design and other strategies designed to potentiate immune system development and function in chickens.