Effects Of Swainsonine On Immunological Function And Its Mechanism Of Mediated Immunity In Mice

Swainsonine(SW) is the primary toxicant in locoweeds within the genera Oxytropis and Astragalus, with a small molecular weight and chemically being indolizidine alkaloid. In recent years, locoweeds have been deeply researched because of its widespread distribution and severity loss in all over the world. However, the study of SW on immunotoxicity had not been developed widely yet. SW mechanism of intoxication has been extensively investigated and has been found to be the potent inhibition of the lysosomalα-mannosidaseâ… which causes the alteration of glycoprotion metabolism and impairment of cellular function as observed vacuolar degeneration in different organs. SW also inhibits Golgi mannosidaseâ…¡, which is involved in the study of anticancer and immunoregulatory activity. SW was found its value of medical science. So understanding the relationship between SW and immune function, and clarification cellular and molecular mechanism of SW will definitely contribute abundant theoretic evidences to clinical application of SW and instructions to reasonable utilization of locoweed resources.In this present paper, requisite SW was extracted from A.variabilis. Mice were selected to study the relationship between SW and immune function by usually methods. After administrated orally with different dosage of SW, the effects of lymphocyte proliferation in normal mice and immunosuppression mice, the changes of T lymphocytes subpopulation, and the secretion of cytokines such as TNF-α,H2O2, as well as the activity of NOS were determined by the methods of lymphocytic transfer proliferation MTT, flow cytometry, ELISA, and enzymic and chemical methods. The results were as follows:1. SW was extracted from A.variabilis and the extraction ratio of SW was 25 mg/kg. The purity of the SW was 98.17% by detected Gas Chromatogram.2. Mice were administrated orally with different concentration of SW in order to obtain the dosage of 0.05,0.2,0.8,3.2 and 6.4 mg/kg SW per day for 21 days to study the relationship between SW and immune function. The results showed that SW at dosage of 6.4 mg/kg can diminished the organ index (thymus and spleen), decreased cellular number in blood, degraded hemoglobin level, reduced the secretory volume of TNF-αand H₂O₂ in blood, depressed activity of NOS. The slices of liver,brain,spleen and kidney were observed the cell vacuolar degeneration. All this results showed that the dosage of SW up to 6.4 mg/kg was signs of toxicity to immune function of mice. There was no signs of vacuolar degeneration by histopathologic examination at low dosage of SW. Especially SW at the dosage of 0.2～0.8 mg/kg increased organ index and cellular number of leucocyte and lymphocyte,hemoglobin secretein blood, augmented the secretion of TNF-αand H2O2, potentialized the activity of NOS.3. The erythrocytolysin test was used to detect the effects of SW on the antibody of erythrocytolysin in blood. The result showed that SW had no effect on the antibody of erythrocytolysin in blood at the dosage range of 0.05～3.2 mg/kg. There was lower erythrocytolysin value than the normal leval. This result indicated that SW at low dosage had no effects on specific humoral immunity in mice, when the dosage reach to 6.4 mg/kg depressed the specific humoral immunity in mice.4. The lymphocytic transfer test was used to detect the lymphocyte proliferation effects of SW in vitro. Spleen lymphocyte was collected and stimulated by ConA,PHA-P and LPS. Proliferative response of spleen lymphocyte was examined by MTT method. SW separately or being combined with ConA and PHA-P showed to stimulate the proliferation of lymphocytes at the concentration 0.2μg/mL. But when being combined with LPS, there was no obviously proliferative response of spleen lymphocyte. SW showed suppression the roliferative response of spleen lymphocyte at the concentration of 4μg/ mL.5. The lymphocytic transfer test was used to detect the lymphocyte proliferation effects of SW in normal mice and immunosuppressive mice in vivo. SW separately or being combined with ConA and PHA-P showed to stimulate the proliferation of lymphocytes at the dosage range of 0.2～0.8 mg/kg; SW showed to antagonism the lymphocytes proliferation of immunosuppressive mice at the appropriate extent. When being combined with LPS, there was no obviously proliferative response of spleen lymphocyte. SW showed suppression the roliferative response of spleen lymphocyte or reinforcement the immunosuppressive action at the dosage 6.4 mg/kg.6. The percentage of T lymphocyte subpopulation in peripheral blood was tested by flow cytometry. SW increased CD3+,CD4+T lymphocyte subpopulation and the CD4+/CD8+ratio at the dosage of SW 0.8 mg/kg or 0.2 mg/kg in normal mice or immunosuppressive mice. The result indicated that the changes of CD3+,CD4+T lymphocyte subpopulation and the CD4+/CD8+ ratio are related with SW improving the specific cellular immunity in mice.7. The effects of SW on immune function of peritoneal macrophages in mice were studied. Peritoneal macrophages were collected and activated by LPS. TNF-αwas examined by ELISA. The activity of NOS and the release of H2O2 were measured by enzymic and chemical methods. MTT colorimetry was used to determine the capability of phagocytosis neutral red and killing tumor cell. The results showed that SW increased activity of phagocytosis, the killing tumor cell and NOS, promoted the release of H2O2 and TNF-αat dosage of 0.2～0.8 mg/kg with dose-effect relation in normal mice and immunosuppressive mice. SW inhibited the activation of macrophage at the dosage of 6.4 mg/kg.All above results can be concluded that SW can influence immune function of mice by two-way regulation and this is correlated with the dosage of SW. SW depresses the cell mediated immunity and humoral-mediated immunity at high dosage of SW. SW can perform its immune function via cellular mediated specificity and non-specificity immunity to enhance immune effects in mice.