Modulation of immune function by conjugated linoleic acid in chickens

This study was carried out to determine the effects of dietary supplementation with conjugated linoleic acid (CLA) on the immune response and fatty acid composition of the spleen in chickens. Three hundred male broiler chicks were randomly allotted into five dietary treatments with different inclusion levels of CLA (0, 5.0, 10.0, 15.0, 20.0 g pure CLA/kg). The relative weights of the thymus and bursa were significantly increased (p<0.05) in chickens fed 5.0 or 10.0 g CLA/kg diet compared with control chickens at age 21 days. Peripheral blood mononuclear cell (PBMC) proliferation and anti-NDV titers were enhanced in 10.0 g CLA/kg dietary treatments (p<0.05). CLA diets resulted in lower PGE2 synthesis than the control diet (p<0.05). Dietary CLA readily incorporated into the phospholipids of immune tissues and altered the fatty acid composition of the spleen with increased LO (n-3) and decreased LA, AA (n-6) relative amounts in chicks. Negative correlation was observed between PGE2 synthesis and lymphocyte proliferation at age 21 days (R2= - 0.677, p<0.05), but no correlation between PGE2 synthesis and anti-NDV titres was observed. The results indicated that dietary CLA could enhance the immune response in chicks, which might be due to changes of eicosanoid production. However, the PGE2-mediated effects cannot be accounted for solely by the overall effect of CLA on immune function.