beta-(1-->3, 1-->4) oat glucan enhances resistance to Eimeria vermiformis infection in immunosuppressed mice.

The effect of intragastrically or parenterally administered beta-glucan, extracted from oats, on the enhancement of disease resistance to Eimeria vermiformis was studied in C57BL/6 mice. Groups of mice were immunosuppressed with dexamethasone (DXM), infected with oocysts of E. vermiformis and treated with oat beta-glucan by the intragastric (i.g.) or subcutaneous (s.c.) routes. Faecal oocyst shedding was reduced in the beta-glucan-treated groups compared to the non-treated group. Immunosuppressed mice which received no beta-glucan treatment showed more severe clinical signs of the disease and a 50% mortality, while minimal clinical signs and no mortality were recorded in the beta-glucan-treated groups. Total IgG, IgG1, IgG2a, IgM and IgA immunoglobulins in the serum of beta-glucan-treated groups were overall higher than those 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 differences were found in the levels of intestinal IgA anti-sporozoite and anti-merozoite immunoglobulins. IFN-gamma- and IL-4-secreting cells, in response to sporozoite antigen, were detected in the spleen and mesenteric 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.