BETA-(1-]3,1-]4) OAT GLUCAN ENHANCES RESISTANCE TO EIMERIA-VERMIFORMIS INFECTION IN IMMUNOSUPPRESSED MICE

The effect of intragastrically or parenterally administered beta-gluca n, extracted from oats, on the enhancement of disease resistance to Ei meria vermiformis was studied in C57BL/6 mice, Groups of mice were imm unosuppressed with dexamethasone (DXM), infected with oocysts of E. ve rmiformis and treated with oat beta-glucan by the intragastric (i.g.) or subcutaneous (s.c.) routes. Faecal oocyst shedding was reduced in t he beta-glucan-treated groups compared to the non-treated group. Immun osuppressed mice which received no beta-glucan treatment showed more s evere clinical signs of the disease and a 50% mortality, while minimal clinical signs and no mortality were recorded in the beta-glucan-trea ted groups. Total IgC, IgC(1), IgG(2a), IgM and IgA immunoglobulins in the serum of beta-glucan-treated groups were overall higher than thos e in the non-treated group. Specific IgG anti-sporozoite and merozoite immunoglobulins in serum were significantly higher in the beta-glucan -treated groups than in the non-treated animals. No significant differ ences were found in the levels of intestinal IgA anti-sporozoite and a nti-merozoite immunoglobulins. IFN-gamma and IL-4-secreting cells, in response to sporozoite antigen, were detected in the spleen and mesent eric lymph nodes of the beta-glucan-treated groups only. In conclusion , the i.g. and s.c. oat beta-glucan treatment increased the resistance to E. vermiformis infection in immunosuppressed mice. (C) 1997 Austra lian Society for Parasitology.