12. Immunosuppression

Aflatoxins intoxications suppress immunoglobulins (IgM, IgG and IgA) and enhance susceptibility of birds to parasitic, viral and bacterial infections. At 0.5 to 1 mg/kg Aflatoxins, these interfere with B and T-lymphocytes functioning [73], apparent alteration of splenic functioning, atrophy of bursa of Fabricius [74], suppresses cell mediated immune response, phagocytosis, and complement system as well as interferon production. Moreover, hematopoietic suppression and anemia have been observed by decrease in RBCs, packed cell volume and hemoglobin [75–78].

AFs decrease total serum proteins due to a reduction in α, β and γ globulins, with IgG being more sensitive than IgM [79] which may cause substantial suppression of acquired immunity from vaccination programs in some disease models. The Low levels of AFB1 appears to affect the vaccinal immunity negatively and may enhance the occurrence of diseases such as Marek's disease, IBD virus, congenitally acquired salmonellosis and duodenal and cecal coccidiosis, etc. even in properly vaccinated flocks [80]. The failure of vaccines is correlated to the immunotoxic effect of toxins which compromise for immune function of birds by decreasing cellmediated immunity and inducing an inflammatory response [81]. Decrease chemotactic ability of leucocytes, impaired heterophils phagocytosis [3] and cellular and serum factors required for optimal phagocytosis can be observed in aflatoxicated chickens. Although dietary AFs depress thrombocyte counts, no effect on their phagocytic activity has been observed [82].
