Effects of polypeptide extracts from grub on immune function of immunosuppressive mice

LI Ke; CAO Shuo; JIAO Simin; SHEN Hong; ZHANG Yonghong

doi:10.13431/j.cnki.immunol.j.20190056

Abstract：This study was performed to investigate the effects of polypeptide extracts from grub on immune function of immunosuppressive mice. The grub polypeptides (GP) were extracted by protease method, and the size of the molecule was determined by electrophoresis. Then the mice were given orally different doses of grub peptides for20 days. All mice except the mice in control group were intraperitoneally injected with cyclophosphamide (CTX) for 3 days before the end of the experiment. The mice were prepared by weighing, collecting blood and aseptic operation for spleen cells. The cell differentiation was induced by lipopolysaccharide (LPS) and concanavalin A (ConA), and cell proliferation and NO level were detected by MTT and Griess method. The serum haemolysin and macrophage phagocytosis were evaluated by spectrophotometry and flow cytometry, while the immunogenicity was analyzed by delayed hypersensitivity. Data showed that the concentration of polypeptide extracted by enzymolysis was 31.63％ and the extraction rate was 37.01 mg/ml, with molecular weight of8 to 9 KDa. The spleen and liver thymus indexes of mice in model group were significantly lower than those of the control and the grub groups. The survival rate of splenetic and myeloid T and B lymphocytes and the secretion of NO in model mice were significantly lower than those of the control and the grub groups. The survival rate of B lymphocyte from bone marrow was significantly higher than that of T lymphocyte, but the secretion of NO in the spleen and bone marrow T lymphocyte was higher than that of B lymphocyte. The absorbance of haemolysin in control group and grub polypeptide group were significantly higher than that in model group. With the increasing of grub polypeptide dose, the content of hemolysin increased gradually, but there was no dose effect relationship. The number of white blood cells in grub groups was higher than that in model group. The ear swelling of the mice in medium and high dose grub polypeptide groups were higher than that of model group. With the increasing of grub dose, the ear swelling thickness increased significantly, and there was a dose effect relationship. The absorbance values of the macrophages from abdominal cavity and bone marrow as well as spleen of grub group were higher than those of model group, and there was a dose effect relationship. The fluorescence intensity of macrophage phagocytosis in grub group was stronger than that of model group, and the number of positive cells of macrophages phagocyting red cell was not significantly higher than that of model group, which suggested that the macrophage phagocytosis was strong. Taken together, polypeptides from grub can significantly enhance immune function in immunosuppressed mice.