ENHANCEMENT OF PROTECTIVE IMMUNITY AND IMMUNO-MODULATION OF LIVER GRANULOMA FORMATION WITH THE COMBINATION OF HUMAN AND MICE ANTI-IDIOTYPIC VACCINE MODEL IN SCHISTOSOMA MANSONI INFECTED MICE
Mohamed A. Ramadan1, Mostafa Abdel-Hamid2, Yehia Shaker Ibrahim3Abdul-Fattah M. Emad3 and Tarek Sakr4
Departments of 1Parasitology, 2Anatomy and 3Internal Medicine, Faculty of Medicine, Minia University
and 4Hepatology Department, Banha Faculty of Medicine, Zagazig University
Schistosomiasis is a direct consequence of the immunological response to ovideposition in the tissue of the host. Vaccination trials have been studied for achieving the highest rates of protection against infection. The regression in pathology has been attributed to modulation due to immunoregulatory events affecting T cell responses to egg antigens. Human anti-idiotypic vaccines (Human anti-Ids) in experimental schistosomiasis achieving varying degrees of resistance to challenge infection with S. mansoni cercariae and mice IgG1 subclass monoclonal antibodies MAbs (Mice anti-Ids, 9F/5D, 3F9C) were selected from a panel of MAbs due to its high reactivity and strict selectivity to Schistosoma antigens. So, the objective of the present study was to investigate the induction of protective immunity to S. mansoni infection and the immunomodulatory effect of the combined immunization by the two vaccine models injected prior to infection. To further characterize the mechanisms associated with such vaccine models, on the protective immunity, on granulomas formation around eggs trapped in liver 8 weeks post- infection and on the distribution of T cell subsets responsible for initiation of immunopathology, the following study was done: mice were divided into 4 groups (40 mice per group), group I: Positive control (mice injected with saline), group II: mice vaccinated with Human anti-Id alone; group III: mice vaccinated with Mice anti-Id alone and group IV: mice vaccinated with the combination of the two vaccines then two weeks after the last immunization, all mice were challenged with 50 S. mansoni cercariae. Mice were sacrificed 8 weeks post-infection, hepatic granuloma diameter, change in worm burden and ova count was evaluated and T cell subsets around the trapped liver granuloma were estimated compared to the control mice. Vaccination of C57BL/6 mice with M anti-Id resulted in ≈ 3% protection and with H anti-Id resulted in ≈ 31% in two experiments of resistance to infection and with the combination of the two vaccines resulted in ≈ 42%. Also, there was marked reduction in granuloma diameter and decrease ratio of T cell subsets (CD4+/CD8+) in the hepatic granulomas in mice vaccinated with the combined vaccines. These results suggested that mice anti-Id monoclonal antibodies combined with human anti-Id could mimic at the T cell level the properties of a protective antigenic epitopes of the irradiated-cercariae vaccine and the targeted selectivity of SEA-conjugate immuno-suppressors with marked reduction of the immunopathology that resulted in liver granulomas formation and subsequent hepatic fibrosis.