The Influence of β-Glucan on Immune Responses in Broiler Chicks

Abstract Beta-1,3 1,6-glucan (β-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 β-glucan in vitro. In addition, day-old broiler chicks were fed a diet containing 0, 20, and 40 mg kg β-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 β-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 β-glucan supplementation increased the macrophage phagocytic activity, anti-sheep red blood cells antibody response post-boost, as well as the PHA-P-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 β-glucan supplemented chicks. Furthermore, the primary and secondary lymphoid organs such as bursa of Fabricius, thymus and spleen were larger in β-glucan-supplemented chicks as compared to the chicks on basal diet. The findings of these studies which showed that β-glucan improves several base-line immune responses in the chicken imply that β-glucan can be used as a possible immunomodulator in food animals such as the chicken.