Document Type : Original Article
IMMUNOLOGY DEPARTMENT, FACULTY OF MEDICINE, TARBIAT MODARRES UNIVERSITY
Introduction: Study the protective effect of mucosal BCG vaccination with subcutaneous against Leishmania major infection in susceptible BALB/c mice
Material and Methods: 6-8 weeks old Male BALB/c mice,were divided to two test groups and four control groups of 20 of mice and then vaccinated. Two test groups vaccinated with appropriate dose of BCG through rectal and subcutaneous routs. They vaccinated one month later with ALM+alum subcutaneously. After receiving the booster dose (21 days later), mice challenged with the injection of 105 leishmania major in the hind footpad and lesion development evaluated every week. Immunologic responses like, delayed type hypersensitivity to Purified Protein Derivatives (PPD), splenocytes proliferation and IFN-γ and IL-5 cytokine production measured in the supernatant of splenocytes culture. Control groups were those that received only ALM+alum or only alum adjuvant subcutaneously. Another control groups challenged with Leishmania without any vaccination or were kept as environmental control without any treatment.
Results: stimulatory effect of BCG on immune system observed in both groups of vaccination according to significant increase (p≤0.05) in delayed type hypersensitivity and IFN-γ production response. increase in splenocytes proliferation observed up to three weeks after challenge. But after that, BCG vaccinated groups had a lot of variations in immune response that finally tend to disease overcome in subcutaneously BCG vaccinated group. The main reason was the significant decrease in IFN-γ production and splenocytes proliferation to rectal group .Parasite dissemination in lymphoid organs were increased significantly in comparison with rectal immunized group. In a different way rectal immunized group showed a high resistant to infection by increase and maintenance of anti-leishmania responses.
Conclusion: Rectal BCG vaccination can induce more stable cellular immune response in comparison to subcutaneous vaccination and make animals protective, by inhibition of L. major dissemination.