| On the basis of the research on the 240 strains of Lactobacillus. casei Zhang(Lb. casei Zhang)isolated from the traditionally home-made koumiss by the Key Laboratory of Dairy Biotechnology and Engineering of Inner Mongolia Agricultural University affiliated to the Ministry of Education. This thesis studies the function of immunity adjustment and anti-tumor activity of one strain of probiotic bacterium Lb. casei Zhang in the body of a laboratory mouse, which contains the potential probiotic properties proved in many past experiments, and explores its possible mechanism of activity.According to the rich studies in the early stage, it is proved that the Lb. casei Zhang has good probiotic properties, and some functions such as reducing cholesterin, antioxidation, and immune adjustment as well as other properties.Based on the studies in the early stage, this thesis further explores the immunity adjustment and anti-tumor activity of Lb. casei Zhang, and then lays a foundation of research in experiment for its further development and application.The experiment on this thesis consists of four parts:Part I:Taking the in vivo experiment, several little mice are orally taken the bacillus killed by high heat and live bacillus made from Lb. casei Zhang in three dosages with high dose, middle dose and low dose and observed for 15 days. Measure the thymus index and spleen index of the mice; observe the function and ability of ConA in the lymphocyte multiplication and macrophage phagocytic function. Test the content of IFN-γ, IL-12, IL-1αand TNF-αin the blood serum in the method of ELISA.Part II:Live bacillus of Lb. casei Zhang is divided into three dosage of high, middle and low and instilled into the mice. And then remove their spleens to calculate the index of spleens at the third, seventh, eleventh and fifteenth day. Take the RT-PCR method to measure the transcription level of IL-2 and IL-2RαmRNA in the spleens.Set about the research on the immune tissue and immune cells of local intestinal mucosa of little mice, study the number counting of Peyer's in the local intestine immune tissue of mice taken Lb. casei Zhang, measure the number of CD3+ and IgA+ of small intestine mucous by the method of immune histochemistry, and then analyze the average optical density with positive signal by using image analysis system so as to know its expressive condition.Part III:Take the little mice with H22 liver cancer for example, 12 days later when the mice are instilled into live bacillus of Lb. casei Zhang in three dosages of high, middle and low, and measure the rate and index of peritoneal macrophage phagocytizing chicken red blood cell in mice by drop technique and calculate the index of spleen and the rate of tumor suppression. Measure the number of Tumor Necrosis Factorβin blood serum by the method of ELISA, check the expression of cancer bcl-2 gene and tumor suppressor gene by immune histochemistry methods, and then explore the possible mechanism of tumor suppressor based on the molecule level.Part IV:Take the mice with H22 liver cancer treated by chemical therapy as models, and then observe the action of toxin-attenuating and efficacy– enhancing caused by Lb. casei Zhang. 12 days later when the mice are injected with Cyclophosphamide in the abdomen and together instilled into live bacillus of Lb. casei Zhang in three dosages of high, middle and low, calculate the index of spleen and rate of tumor suppression, record the Peyer's in the local immune tissue of mice's intestine, check the expression of PCNA in tumor cells by using the method of in situ hybridization, and check the cell cycle and apoptosis rate of tumor cells by using flow cytometer with propidium iodide technology.We reach a general conclusion based on the above experiments: the Lb. casei Zhang with evident probiotic properties have many active adjustment actions on cell immunity, humoral immunity and intestine mucosal immunity of laboratory little mice; have an evident inhibitory action of growth on the transplanted tumor of H22 liver cancer-bearing mice; have an evident action of toxin-attenuating and efficacy– enhancing on the Cyclophosphamide in chemical therapy. Its mechanism to resist tumor probably is to inhibit the increase of tumor cells and induce the apoptosis of tumor cells through strengthening the immunity of mice with tumor.
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