The immune adjuvant response of polysaccharides from Atractylodis macrocephalae Koidz in chickens vaccinated against Newcastle disease (ND)

•RAMPStp and RAMPS60c could significantly enhance T lymphocyte proliferation and increase antibody titers.•RAMPStp and RAMPS60c could improve the percentages of CD4+ and CD8+ T cells.•RAMPStp and RAMPS60c could promote lymphocytes enter into S and G2/M phases.•The glucose side chains of the polymer could be more responsible for the immune-enhancing activity.•RAMPStp would be anticipated as a component of new-type immunopotentiator. Build on our previous research, polysaccharides from the rhizome of Atractylodis macrocephalae Koidz (RAMPS), RAMPStp and RAMPS60c were prepared and the structural characterization and immune response of ND vaccine in chicken were investigated. Immune organ index, Lymphocyte proliferation, antibody titers, cell cycle distribution, and percentages of CD4+ and CD8+ cells were determined. GPC analysis showed that the Mn of RAMPS with two peaks were 1.29×105 and 1.74×103, respectively. GC–MS analysis revealed that RAMPS was composed of glucose, mannose, arabinose, galactose, xylose, d-Ribose and rhamnose, with mass percentages of 66.39%, 21.24%, 5.64%, 2.65%, 2.30%, 1.15% and 0.64%, respectively. NMR spectroscopic analysis demonstrated that a preliminary structure of RAMPS was proposed as 1,3-linked β-d-Galp and 1,6-linked β-d-Galpresidues. In vivo test showed that RAMPStp and RAMPS60c could promote peripheral lymphocytes proliferation and entering into S and G2/M phases, enhance serum HI antibody titer and effectively improve the percentages of CD4+ and CD8+ T cells in chickens vaccinated with ND vaccine at most time points. The actions of RAMPStp and RAMPS60c were stronger than that of Lev, and RAMPStp presented the best efficacy. These results indicated that RAMPStp and RAMPS60c characterize of the immune-enhancing activity and RAMPStp possessed the strongest activity. It would be anticipated as a component of new-type immunopotentiator.