The Immune Organ Characteristics Of Lanzhou Fat-tailed Sheep

The immune system is composed of immune cells,immune tissues and immune organs,which includes central immune organs and peripheral immune organs.Immune system is the self-protection system recognizes and eliminates the antigenic substances to maintain the body function.The normal function of immune organs is essential for improving sheep shed productions.In order to protect the unique local species in China,the Lanzhou fat-tailed sheep?LFTS?effectively,study the characteristics of its immune organs,histological staining technology were used to observe the main immune organ in lanzhou fat-tailed sheep,immuno-histochemical and real-time fluorescent quantitative PCR techniques were used to detect IgG,IL-2and CD21 in the immune organs.The results showed as follows:1.In lanzhou fat-tailed sheep,the organ index of thymus was 0.09±0.01%,the cortical thickness was 189.00±3.79?m,the A_PC and A_PM was 0.68±0.03 and 0.26±0.01respectively,and the thymic bodies per mm² was 8.00±0.56.2.The mature lymphoid follicles in the superficial cervical lymph nodes of lanzhou fat-tailed sheep?25.70±1.40?was significantly higher than that in mesenteric lymph nodes,pharyngeal tonsil and spleen?P<0.05?.There was no significant difference in the number of mature lymphoid follicles in the spleen and mesenteric lymph nodes?P>0.05?.The A_PC of tonsil?0.47±0.03?was significantly higher than that of the spleen,superficial cervical lymph nodes and mesenteric lymph nodes?P<0.05?.There was no significant difference between the spleen,cervical and mesenteric lymph nodes?P>0.05?.The A_PM of tonsil?0.42±0.01?was significantly lower than that of mesenteric lymph node,cervical superficial lymph node and spleen medulla?P<0.05?.However,there was no significant difference in A_PM between the spleen,cervical and mesenteric lymph nodes?P>0.05?.The highest collagen fiber content ratio of mesenteric lymph node?32.00±2.10?was significantly higher than that of tonsil?24.00±2.00,P<0.05?.3.Immunohistochemical staining results showed that the distribution and expression of IgG,IL-2 and CD21 were different in each immune organ of lanzhou fat-tailed sheep.IgG,IL-2 and CD21 were all located in the cytoplasm,and a small number of cell nuclei of IL-2 were immunopositive in the mesenteric lymph node and spleen.The highest expression of IgG in thymus was?83.40±1.70?and significantly higher than that of peripheral immune organ?P<0.05?.The highest expression level in peripheral immune organs was 58.17±1.88 in mesenteric lymph node,which was significantly higher than that in spleen?50.31±1.22?and tonsil?30.76±1.30,P<0.05?.The highest expression of IL-2 in thymus of central immune organs was?56.19±0.99?significantly higher than that of peripheral immune organs?P<0.05?.The highest expression was found in the spleen of the peripheral immune organ?19.79±0.21?,which was significantly higher than that in the tonsil?P<0.05?.The highest expression of CD21 was found in the spleen of peripheral immune organs?75.03±0.97?,followed by the tonsil?55.65±0.87?,which was significantly higher than that in the thymus of central immune organs?46.00±1.00?.4.The results of real-time quantitative PCR showed that the expression levels of IgG and IL-2 mRNA in the thymus of lanzhou fat-tailed sheep were 3.19±0.04,5.5±0.04.They are significantly higher than that of tonsil?1.00±0.01,P<0.05?.The expression level of CD21 mRNA in spleen of lanzhou fat-tailed sheep?3.47±0.03?was significantly higher than that of superficial cervical lymph nodes?1.00±0.01?.To sum up,the structure of each immune organ of lanzhou fat-tailed sheep is basically similar to that of other mammals,and the organ index of thymus of lanzhou fat-tailed sheep are higher than those of small-tailed han sheep of the same age.The expression levels of IgG and IL-2 in thymus of central immune organ of lanzhou fat-tailed sheep were significantly higher than that of peripheral immune organs?P<0.05?.CD21 expression in the spleen and tonsil of peripheral immune organs of lanzhou fat-tailed sheep was significantly higher than that in central immune organs?P<0.05?.All three proteins are located in the cytoplasm,with a small amount of IL-2located in the nucleus of mesenteric lymph node and spleen.