Pathology of spleen in chickens fed on a diet deficient in methionine

The purpose of this 42-day study was to investigate the effects of methionine deficiency on spleen by determining the relative weight, morphological changes of spleen, cell cycle and apoptosis of splenocytes, and oxidative markers of serum and spleen. One hundred and twenty one-day-old avian broilers were randomly divided into two groups and fed on a control diet (starter diet, methionine 0.50%; grower diet, methionine 0.40%) and methionine deficient diet (starter diet, methionine 0.26%; grower diet, methionine 0.28%) for 6 weeks. The relative weight of spleen was lighter in methionine deficiency than control group. Histopathologically, lymphopenia and congestion were observed. Ultrastructurally, there were more apoptosis lymphocytes in spleen and the mitochondria of lymphocytes were swelled in methionine deficiency. By flow cytometry, the G0/G1 phase of the cell cycle of the spleen was much higher (P < 0.01), and the S, G2+M phases and proliferating index were lower (P < 0.01) in methionine deficiency than in control group. And the percentage of apoptotic cells in the spleen was significantly increased in methionine deficiency (P < 0.01).The superoxide dismutase and glutathione peroxidase activities, and abilities to inhibit hydroxyl radicals were greatly decreased while the malondialdehyde contents were markedly increased in methionine deficiency. It was concluded that methionine deficiency could restraine the development of the spleen by cell cycle arrest and increased apoptosis, cause splenic lesions and reduce splenic antioxidant function. The splenic function should be finally impaired and then the immune function could be impacted in chickens.