Immunological Effect of Polysaccharide Extracted from Pseudomonas aeruginosa against Leishmania donovani in mice


ABSTRACT:BACKGROUND:Visceral leishmaniasis is a serious disease with high pathoogenicity. It was noticed that Polysaccharide extracted from Pseudomonas aeruginosa had the ability to induce both cellular & humoral immunity response against bacteria, fungi & parasites.OBJECTIVE:The aim of this study was to know the immunological effects of polysaccharide extracted from Pseudomonas aeruginosa before & after the infection of BALB/c mice with Leishmania donovani in trial to provide a method for prevention of the disease in human.METHODS:174 male BALB/c mice were divided into control & experimental groups with each group consisting of six animals. The experimental groups injected intraperitoneally (i.p) with 0.2 ml phosphate buffer saline (PBS) containing 1×108 parasite. Cerdain groups were injected intraperitoneally by polysaccharide (PS) at doses of 100, 150, 250 μg on day 3, 6, and daily for 6 days before infection with Leishmania donovani. These animals were sacrified after 8 weeks. Other groups were injected intraperitoneally with polysaccharides on day 7 post infection at the doses of 100, 150, 250, μg, 6 animals were sacrified after 2, 4, 6, 8 weeks. Total & differential count of leukocytes, measurement of spleen & liver weight and index, measurement of cellular immune response, histopathological changes liver and spleen were carried out.RESULTS:This study showed an increase in the total count of leukocyte accompanied by an increase in lymphocyte with decrease in monocyte percent in mice treated with polysaccharide before and after infection with Leishmania donovani which were statistically significant. Reduction in liver & spleen weights & their index in all treated groups was noticed before & after infection. The cellular immune response represented by delayed hypersensitivity has been enhanced in the mice treated with polysaccharide before &after infection. In treated groups, histopathological studies of mice showed hepatocyte hypertrophy, infiltration of the inflammatory cells in liver before & after infection. In spleen showed an increase in lymphocytes & monocytes in red pulp, while the infected mice (non treated) showed a necrotic foci, loss of architecture of both liver & spleen & obvious granulomatous inflammation in liver.CONCLUSION:Polysaccharidde extracted from Pseudomonas aeruginosa induced immunological activity by activation of cell mediated responses, stimulated an increase in WBC count & lymphocytes with minor histoptholgical changes in liver and spleen.