Three hundred and sixty 14-day-old chickens were divided into seven groups. The chickens, except for blank control group, were vaccinated with Newcastle disease vaccine, repeated at 28 days old. At the same time of the first vaccination, the chickens in three astragalus polysaccharide-oxymatrine (AP-OM) groups were orally administrated respectively with the mixture of AP-OM at high, medium and low concentrations, in astragalus polysaccharide (AP) group and oxymatrine (OM) group, with corresponding medicine, in non-medicine (NM) control group, with equal volume of physiological saline, once a day for 3 successive days. On 14, 21, 28, 35 and 42 days after the first vaccination, the changes of peripheral lymphocyte proliferation and serum antibody titers of the chickens were determined by MTT method and hemagglutination inhibition test. On 14, 28 and 42 days after the first vaccination, the serum IL-2 concentration was determined by Enzyme-linked Immunosorbent Assay (ELISA). The results showed that at most time points, the lymphocyte proliferation, antibody titers and IL-2 concentrations of 5 medicine-administrating groups were significantly higher than that of corresponding NM group. At some time points, the lymphocyte proliferation, antibody titers and IL-2 concentrations in high and medium doses of AP-OM groups were significantly or numberly higher than those in AP group and OM group. It indicated that AP-OM could significantly improve the immune efficacy of Newcastle disease vaccine, astragalus polysaccharide and oxymatrine possessed synergistical immunoenhancement.
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