The influence of beta-glucan on immune responses in broiler chicks

Beta-1,3/1,6-glucan (beta-glucan) was tested as a possible immunomodulator. Chicken macrophages from a macrophage cell line MQ-NCSU and from abdominal exudate of broiler chickens were exposed to various concentrations of beta-glucan in vitro. In addition, day-old broiler chicks were fed a diet containing 0, 20, and 40 mg/kg beta-glucan in the starter and 0, 20, and 20 mg/kg in the grower diet. Several baseline immune parameters were examined following such exposures. The results showed that beta-glucan exposure increased nitrite and interleukin-1 (IL-1) production as well as induced macrophage to proliferate in culture. However, IL-6 production was not affected. Dietary beta-glucan supplementation increased the macrophage phagocytic activity, anti-sheep red blood cells antibody response post-boost, as well as the PHAP-mediated lymphoproliferative response measured as a toe-web swelling. The percentage of CD4(+), CD8(+), and CD4(+)/CD8(+) double positive lymphocytes in the intestinal intraepithelial leukocytes was increased in beta-glucan supplemented chicks. Furthermore, the primary and secondary lymphoid organs such as bursa of Fabricius, thymus and spleen were larger in beta-glucan-supplemented chicks as compared to the chicks on basal diet. The findings of these studies which showed that beta-glucan improves several baseline immune responses in the chicken imply that beta-glucan can be used as a possible immunomodulator in food animals such as the chicken.