Enhancement of peripheral blood CD8+ T cells and classical swine fever antibodies by dietary β-1,3/1,6-glucan supplementation in weaned piglets.
The experiment was conducted to evaluate the effect of dietary supplementation with 0, 50, 100 and 200 mg/kg of β-1,3/1,6-glucan extracted from Saccharomyces cerevisiae on cellular immune responses and classical swine fever virus (CSFV) antibody production of weaned piglets. Thirty-two (Landrace × Large White; 26 days old; 7.05±0.25 kg body weight) castrated male piglets were randomly allocated to four treatments, eight pigs per treatment. All piglets were vaccinated with live-attenuated Chinese strain cell vaccines at 26 days of age. The results showed that dietary supplementation with β-1,3/1,6-glucan could significantly (P<0.01) enhance peripheral blood lymphocyte proliferation activity in weaned piglets after 14 days administration, whereas no significant effect (P>0.05) was observed on day 28. Dietary β-1,3/1,6-glucan supplementation could significantly enhance CSFV antibody blocking rate (P<0.05) on days 14 and 21 after inoculation. Although dietary β-1,3/1,6-glucan supplementation did not significantly influence (P>0.05) lymphocyte subgroups on day 14, high levels of β-1,3/1,6-glucan (100 and 200 mg/kg) increased the percentage of cytotoxic/suppressor lymphocytes (CD8+) significantly (P<0.05), decreased the ratio of CD4+/CD8+ significantly (P<0.05) and increased the percentage of total T lymphocytes (CD3+) on day 28. These results suggest that β-1,3/1,6-glucan may have a beneficial effect on the immune system of swine, and dietary β-1,3/1,6-glucan supplementation had a transient impact on lymphocyte proliferation activity. The CSFV antibody blocking rate and the percentage of peripheral blood CD8+ T cells could be enhanced by continuous β-1,3/1,6-glucan supplementation. These findings support the potential application of β-1,3/1,6-glucan as a prophylactic agent in increasing animal immune functions and controlling CSF disease.